[03-Developer] #260 in-app tool calling (Gemma 4 multi-turn)

ADR-0005 in-process tool runtime — 6 tools (catalog 2 + tracker 2 +
habit 2), ToolDispatcher with JSON-schema validation + modal ConfirmGate
for destructive ops, multi-turn LlmChatSession abstraction wired to
flutter_gemma 0.16.5 (ToolChoice.auto), ChatSessionController with
MAX_TURNS=4 safety + 8-turn history hint, ChatScreen entry behind AI
opt-in. R3/R7/R8 enforced inside handlers. 41 new tests (envelope,
catalog/tracker/habit tools, dispatcher, controller loop) — 151 total
passing.

Refs #260

app/test/ai/tools/_tool_test_helpers.dart

@@ -0,0 +1,48 @@
+import 'package:drift/drift.dart' as drift;
+import 'package:life_helper/ai/tools/tool_definition.dart';
+import 'package:life_helper/core/constants.dart';
+import 'package:life_helper/core/time.dart';
+import 'package:life_helper/data/catalog/catalog_repository.dart';
+import 'package:life_helper/data/db/app_database.dart';
+import 'package:life_helper/data/db/daos/habit_dao.dart';
+import 'package:life_helper/data/db/daos/tracker_dao.dart';
+import 'package:life_helper/data/seed/seed_importer.dart';
+import 'package:life_helper/domain/models/frame_pattern.dart';
+
+import '../../data/seed/test_seeds.dart';
+
+/// Tool tests share a tiny in-memory bootstrap. Returns the assembled
+/// [ToolDeps] plus the underlying [AppDatabase] so callers can close it
+/// in tearDown.
+Future<({AppDatabase db, ToolDeps deps})> bootstrapToolDeps() async {
+  final db = AppDatabase.memory();
+  // default user (seed importer doesn't insert users — bootstrap does).
+  await db.into(db.users).insert(UsersCompanion.insert(
+        id: kLocalDefaultUserId,
+        displayName: const drift.Value('Test'),
+        createdAt: nowKst().toIso8601String(),
+      ));
+  await SeedImporter(db, loadAsset: testStubLoader).importIfNeeded();
+  final patterns = await db.select(db.framePatterns).get();
+  final framePatterns = patterns
+      .map((r) => FramePatternModel(
+            id: r.id,
+            domain: r.domain,
+            avoidanceKeyword: r.avoidanceKeyword,
+            l0Example: r.l0Example,
+            l1SimpleReplace: r.l1SimpleReplace,
+            l2Suggestion: r.l2Suggestion,
+            l3Identity: r.l3Identity,
+          ))
+      .toList();
+  return (
+    db: db,
+    deps: ToolDeps(
+      habitDao: HabitDao(db),
+      trackerDao: TrackerDao(db),
+      catalog: CatalogRepository(db),
+      framePatterns: framePatterns,
+      userId: kLocalDefaultUserId,
+    ),
+  );
+}