[Designer] #215 Polish AI settings + frame suggestion surfaces

- frame_suggestion_dialog: hide exception detail in error path, redesign
  candidate card as Card+InkWell with L2/L3 colored level badge (secondary
  vs primary), remove confidence % surface.
- settings_screen: download tile gains state label + colored progress text,
  rounded LinearProgressIndicator, FilledButton.tonalIcon for resume/retry.
  _friendlyError() maps internal codes (network:/http /stream:/sha mismatch)
  to user-readable Korean. Opt-in/out dialogs reorganized with _Bullet rows;
  beta disclaimer reworded; _describe() friendlier copy.

Polish only — no behavior change. analyze 0, 71 tests pass, APK 10.3s.

Refs #215

app/lib/ui/screens/settings_screen.dart

@@ -85,8 +85,7 @@ class _AiSection extends ConsumerWidget {
         const Padding(
           padding: EdgeInsets.fromLTRB(16, 8, 16, 16),
           child: Text(
-            'OQ-1 미해결: 정확한 모델 URL + SHA 가 픽스되기 전까지 '
-            '다운로드는 동작하지 않습니다. (Architect/Developer 인계 사항)',
+            '베타 기능 · 모델 다운로드가 정식 제공되기 전까지 일부 동작이 제한됩니다.',
             style: TextStyle(fontSize: 12, color: Colors.grey),
           ),
         ),
@@ -97,13 +96,13 @@ class _AiSection extends ConsumerWidget {
   String _describe(ModelAvailability a) {
     switch (a) {
       case ModelAvailability.ready:
-        return '사용 가능';
+        return '준비 완료 — 새 습관 만들기에서 ✨ AI 제안을 쓸 수 있어요';
       case ModelAvailability.missing:
-        return '미설치 — 토글을 켜면 다운로드를 시작합니다';
+        return '아직 받지 않았어요 — 위 토글을 켜면 다운로드합니다';
       case ModelAvailability.corrupt:
-        return '손상됨 — 토글을 끄고 다시 켜주세요';
+        return '파일이 손상됐어요 — 끄고 다시 켜면 새로 받습니다';
       case ModelAvailability.downloading:
-        return '다운로드 중 / 일시정지됨';
+        return '다운로드 중';
     }
   }
 
@@ -117,11 +116,19 @@ class _AiSection extends ConsumerWidget {
       context: context,
       builder: (_) => AlertDialog(
         title: const Text('AI 도움 켜기'),
-        content: const Text(
-          'Gemma 4 E2B 모델 ≈ 1.5GB 를 다운로드합니다.\n'
-          '- WiFi 권장\n'
-          '- 모든 처리는 단말에서만 일어나며, 입력 텍스트는 외부로 전송되지 않습니다.\n'
-          '- 끄면 즉시 삭제됩니다.',
+        content: Column(
+          mainAxisSize: MainAxisSize.min,
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: const [
+            Text(
+              '단말에서 동작하는 AI 모델을 내려받습니다.',
+              style: TextStyle(fontWeight: FontWeight.w600),
+            ),
+            SizedBox(height: 12),
+            _Bullet('파일 크기: 약 1.5GB'),
+            _Bullet('WiFi 연결을 권장합니다'),
+            _Bullet('모든 처리는 단말에서만 일어나며, 입력 텍스트는 외부로 전송되지 않습니다'),
+          ],
         ),
         actions: [
           TextButton(
@@ -130,7 +137,7 @@ class _AiSection extends ConsumerWidget {
           ),
           FilledButton(
             onPressed: () => Navigator.of(context).pop(true),
-            child: const Text('동의 후 다운로드'),
+            child: const Text('동의하고 다운로드'),
           ),
         ],
       ),
@@ -142,9 +149,22 @@ class _AiSection extends ConsumerWidget {
       context: context,
       builder: (_) => AlertDialog(
         title: const Text('AI 도움 끄기'),
-        content: const Text(
-          '모델 파일 ≈ 1.5GB 가 즉시 삭제됩니다. '
-          '다시 켜면 다시 다운로드해야 합니다.',
+        content: Column(
+          mainAxisSize: MainAxisSize.min,
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: const [
+            Text('모델 파일이 단말에서 삭제됩니다.'),
+            SizedBox(height: 8),
+            Text(
+              '약 1.5GB 의 저장공간이 확보돼요.',
+              style: TextStyle(fontSize: 13, color: Colors.grey),
+            ),
+            SizedBox(height: 4),
+            Text(
+              '다시 켜면 다시 다운로드해야 합니다.',
+              style: TextStyle(fontSize: 13, color: Colors.grey),
+            ),
+          ],
         ),
         actions: [
           TextButton(
@@ -161,6 +181,27 @@ class _AiSection extends ConsumerWidget {
   }
 }
 
+class _Bullet extends StatelessWidget {
+  final String text;
+  const _Bullet(this.text);
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+      padding: const EdgeInsets.only(bottom: 4),
+      child: Row(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          const Padding(
+            padding: EdgeInsets.only(top: 6, right: 8),
+            child: Icon(Icons.circle, size: 5),
+          ),
+          Expanded(child: Text(text, style: const TextStyle(fontSize: 14))),
+        ],
+      ),
+    );
+  }
+}
+
 /// AC2: shows download progress + pause/resume/restart controls.
 class _DownloadProgressTile extends StatelessWidget {
   final DownloadProgress progress;
@@ -169,17 +210,26 @@ class _DownloadProgressTile extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final scheme = Theme.of(context).colorScheme;
     final controller = ref.read(modelDownloadControllerProvider.notifier);
     final pct = progress.totalBytes > 0
         ? (progress.bytesReceived / progress.totalBytes).clamp(0.0, 1.0)
         : null;
     final pctText = pct != null
         ? '${(pct * 100).toStringAsFixed(0)}%'
-        : '계산 중...';
+        : '계산 중';
     final size =
         '${_fmtBytes(progress.bytesReceived)}'
         '${progress.totalBytes > 0 ? " / ${_fmtBytes(progress.totalBytes)}" : ""}';
 
+    final (stateLabel, stateColor) = switch (progress.state) {
+      DownloadState.downloading => ('다운로드 중', scheme.primary),
+      DownloadState.paused => ('일시정지됨', scheme.outline),
+      DownloadState.failed => ('실패', scheme.error),
+      DownloadState.completed => ('준비 완료', Colors.green.shade700),
+      DownloadState.idle => ('대기 중', scheme.outline),
+    };
+
     Widget controls;
     switch (progress.state) {
       case DownloadState.downloading:
@@ -190,47 +240,74 @@ class _DownloadProgressTile extends StatelessWidget {
         );
         break;
       case DownloadState.paused:
-        controls = TextButton.icon(
+        controls = FilledButton.tonalIcon(
           icon: const Icon(Icons.play_arrow),
           label: const Text('재개'),
           onPressed: controller.resume,
         );
         break;
       case DownloadState.failed:
-        controls = TextButton.icon(
+        controls = FilledButton.tonalIcon(
           icon: const Icon(Icons.refresh),
           label: const Text('다시 시도'),
           onPressed: controller.resume,
         );
         break;
       case DownloadState.completed:
-        controls = const Text('완료', style: TextStyle(color: Colors.green));
-        break;
       case DownloadState.idle:
         controls = const SizedBox.shrink();
         break;
     }
 
     return Padding(
-      padding: const EdgeInsets.fromLTRB(16, 0, 16, 8),
+      padding: const EdgeInsets.fromLTRB(16, 0, 16, 12),
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.stretch,
         children: [
           Row(
             children: [
-              Expanded(child: Text('$size · $pctText')),
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Text(
+                      stateLabel,
+                      style: TextStyle(
+                        fontSize: 13,
+                        fontWeight: FontWeight.w600,
+                        color: stateColor,
+                      ),
+                    ),
+                    const SizedBox(height: 2),
+                    Text(
+                      progress.state == DownloadState.completed
+                          ? size
+                          : '$size · $pctText',
+                      style: TextStyle(
+                        fontSize: 12,
+                        color: scheme.onSurfaceVariant,
+                      ),
+                    ),
+                  ],
+                ),
+              ),
               controls,
             ],
           ),
-          const SizedBox(height: 4),
-          LinearProgressIndicator(value: pct),
-          if (progress.state == DownloadState.failed &&
-              progress.errorMessage != null)
+          const SizedBox(height: 6),
+          ClipRRect(
+            borderRadius: BorderRadius.circular(4),
+            child: LinearProgressIndicator(
+              value: pct,
+              minHeight: 6,
+            ),
+          ),
+          if (progress.state == DownloadState.failed)
             Padding(
-              padding: const EdgeInsets.only(top: 4),
+              padding: const EdgeInsets.only(top: 6),
               child: Text(
-                '에러: ${progress.errorMessage}',
-                style: const TextStyle(fontSize: 12, color: Colors.red),
+                _friendlyError(progress.errorMessage),
+                style: TextStyle(fontSize: 12, color: scheme.error),
               ),
             ),
         ],
@@ -238,6 +315,26 @@ class _DownloadProgressTile extends StatelessWidget {
     );
   }
 
+  /// Maps internal error codes to user-friendly Korean messages.
+  /// Hides technical detail (HTTP status, stack) — keeps the next action
+  /// obvious instead.
+  String _friendlyError(String? raw) {
+    if (raw == null) return '다운로드에 실패했어요. 다시 시도해주세요.';
+    if (raw.startsWith('network:')) {
+      return '네트워크 연결을 확인하고 다시 시도해주세요.';
+    }
+    if (raw.startsWith('http ')) {
+      return '서버 응답이 올바르지 않습니다. 잠시 후 다시 시도해주세요.';
+    }
+    if (raw.startsWith('stream:')) {
+      return '다운로드가 중단되었어요. 다시 시도하면 이어받습니다.';
+    }
+    if (raw == 'sha mismatch') {
+      return '파일이 손상되었어요. 다시 시도하면 처음부터 받습니다.';
+    }
+    return '다운로드에 실패했어요. 다시 시도해주세요.';
+  }
+
   String _fmtBytes(int bytes) {
     if (bytes < 1024) return '$bytes B';
     if (bytes < 1024 * 1024) return '${(bytes / 1024).toStringAsFixed(1)} KB';

app/lib/ui/widgets/frame_suggestion_dialog.dart

@@ -33,9 +33,11 @@ class FrameSuggestionDialog extends ConsumerWidget {
             height: 120,
             child: Center(child: CircularProgressIndicator()),
           ),
-          error: (e, _) => Padding(
-            padding: const EdgeInsets.all(8),
-            child: Text('AI 제안을 받지 못했습니다. 직접 입력해주세요.\n($e)'),
+          error: (e, _) => const Padding(
+            padding: EdgeInsets.all(8),
+            child: Text(
+              'AI 제안을 받지 못했어요.\n직접 입력하셔도 괜찮습니다.',
+            ),
           ),
           data: (candidates) {
             if (candidates.isEmpty) {
@@ -88,14 +90,49 @@ class _CandidateCard extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final scheme = Theme.of(context).colorScheme;
+    final isL3 = candidate.level == FrameLevel.l3;
+    final levelLabel = isL3 ? '정체성' : '조건부 긍정';
+    final levelCode = isL3 ? 'L3' : 'L2';
+    final levelColor = isL3 ? scheme.primary : scheme.secondary;
     return Card(
-      child: ListTile(
-        title: Text(candidate.framedText),
-        subtitle: Text(
-          '${candidate.level == FrameLevel.l3 ? "L3 · 정체성" : "L2 · 조건부 긍정"} '
-          '· 신뢰도 ${(candidate.confidence * 100).toInt()}%',
-        ),
+      margin: const EdgeInsets.symmetric(vertical: 4),
+      child: InkWell(
         onTap: onTap,
+        borderRadius: BorderRadius.circular(8),
+        child: Padding(
+          padding: const EdgeInsets.fromLTRB(12, 10, 12, 12),
+          child: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Row(
+                children: [
+                  Container(
+                    padding:
+                        const EdgeInsets.symmetric(horizontal: 6, vertical: 2),
+                    decoration: BoxDecoration(
+                      color: levelColor.withValues(alpha: 0.12),
+                      borderRadius: BorderRadius.circular(4),
+                    ),
+                    child: Text(
+                      '$levelCode · $levelLabel',
+                      style: TextStyle(
+                        fontSize: 11,
+                        color: levelColor,
+                        fontWeight: FontWeight.w600,
+                      ),
+                    ),
+                  ),
+                ],
+              ),
+              const SizedBox(height: 6),
+              Text(
+                candidate.framedText,
+                style: Theme.of(context).textTheme.bodyLarge,
+              ),
+            ],
+          ),
+        ),
       ),
     );
   }