Switch to user Chrome CDP for YouTube transcript, fix auth and ads

- Replace Playwright standalone browser with CDP connection to user Chrome
  (bypasses YouTube bot detection by using logged-in Chrome session)
- Add video playback, ad detection/skip, and play confirmation before transcript extraction
- Extract transcript JS to separate resource files (fix SyntaxError in evaluate)
- Add ytInitialPlayerResponse-based transcript extraction as primary method
- Fix token refresh: retry on network error during backend restart
- Fix null userId logout, CLOB type hint for structured_content
- Disable XFCE screen lock/screensaver
- Add troubleshooting entries (#10-12) and YouTube transcript guide

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sundol-backend/src/main/resources/youtube-transcript-extract.js

@@ -0,0 +1,33 @@
+() => {
+  var selectors = [
+    'ytd-transcript-segment-renderer .segment-text',
+    'yt-formatted-string.segment-text',
+    '#segments-container yt-formatted-string',
+    'ytd-transcript-segment-list-renderer .segment-text',
+    'ytd-transcript-segment-renderer yt-formatted-string',
+    'ytd-engagement-panel-section-list-renderer yt-formatted-string.ytd-transcript-segment-renderer'
+  ];
+  for (var s = 0; s < selectors.length; s++) {
+    try {
+      var segs = document.querySelectorAll(selectors[s]);
+      if (segs.length > 0) {
+        var texts = [];
+        for (var i = 0; i < segs.length; i++) {
+          var txt = segs[i].textContent.trim();
+          if (txt.length > 0) texts.push(txt);
+        }
+        if (texts.length > 0) return texts.join(' ');
+      }
+    } catch(e) {}
+  }
+  // 최후 수단: engagement panel 내 모든 텍스트
+  var panel = document.querySelector('ytd-engagement-panel-section-list-renderer[target-id="engagement-panel-searchable-transcript"]');
+  if (panel) {
+    var body = panel.querySelector('#body, #content');
+    if (body) {
+      var allText = body.innerText.trim();
+      if (allText.length > 100) return allText;
+    }
+  }
+  return '';
+}

sundol-backend/src/main/resources/youtube-transcript-from-page.js

@@ -0,0 +1,72 @@
+() => {
+  try {
+    // 방법 1: ytInitialPlayerResponse에서 직접 자막 데이터 추출
+    var playerResponse = null;
+    if (typeof ytInitialPlayerResponse !== 'undefined') {
+      playerResponse = ytInitialPlayerResponse;
+    }
+    if (!playerResponse) {
+      // 페이지 소스에서 추출 시도
+      var scripts = document.querySelectorAll('script');
+      for (var i = 0; i < scripts.length; i++) {
+        var text = scripts[i].textContent;
+        if (text && text.indexOf('ytInitialPlayerResponse') !== -1) {
+          var match = text.match(/ytInitialPlayerResponse\s*=\s*(\{.*?\});/s);
+          if (match) {
+            try { playerResponse = JSON.parse(match[1]); } catch(e) {}
+          }
+        }
+      }
+    }
+
+    if (!playerResponse) return JSON.stringify({error: 'no_player_response'});
+
+    // captionTracks 추출
+    var captions = playerResponse.captions;
+    if (!captions) return JSON.stringify({error: 'no_captions'});
+
+    var renderer = captions.playerCaptionsTracklistRenderer;
+    if (!renderer) return JSON.stringify({error: 'no_renderer'});
+
+    var tracks = renderer.captionTracks;
+    if (!tracks || tracks.length === 0) return JSON.stringify({error: 'no_tracks'});
+
+    // 언어 우선순위: ko > en > 첫 번째
+    var selectedTrack = null;
+    for (var t = 0; t < tracks.length; t++) {
+      if (tracks[t].languageCode === 'ko') { selectedTrack = tracks[t]; break; }
+    }
+    if (!selectedTrack) {
+      for (var t = 0; t < tracks.length; t++) {
+        if (tracks[t].languageCode === 'en') { selectedTrack = tracks[t]; break; }
+      }
+    }
+    if (!selectedTrack) selectedTrack = tracks[0];
+
+    var baseUrl = selectedTrack.baseUrl;
+    if (!baseUrl) return JSON.stringify({error: 'no_base_url'});
+
+    // fmt=json3 추가
+    if (baseUrl.indexOf('fmt=') === -1) {
+      baseUrl += '&fmt=json3';
+    }
+
+    // 브라우저 내에서 fetch로 자막 데이터 가져오기
+    return fetch(baseUrl, {credentials: 'include'})
+      .then(function(res) { return res.text(); })
+      .then(function(text) {
+        if (!text || text.length === 0) {
+          // fmt=json3 실패 시 fmt 없이 재시도 (XML)
+          var xmlUrl = baseUrl.replace('&fmt=json3', '');
+          return fetch(xmlUrl, {credentials: 'include'})
+            .then(function(res2) { return res2.text(); })
+            .then(function(xmlText) {
+              return JSON.stringify({type: 'xml', data: xmlText, lang: selectedTrack.languageCode});
+            });
+        }
+        return JSON.stringify({type: 'json3', data: text, lang: selectedTrack.languageCode});
+      });
+  } catch(e) {
+    return JSON.stringify({error: e.message});
+  }
+}