fix: real-time HLS interception via content script (architectural overhaul)

Previous approach (DOM snapshot via executeScript) failed on Pornhub because:
- Video player loads asynchronously via JavaScript
- HLS manifest arrives via XHR/fetch AFTER page render
- <video> element only shows blob: URL, not the actual manifest

New approach:
- Content script injects interceptor into MAIN world at document_start
- Interceptor patches XMLHttpRequest and fetch() to capture .m3u8 URLs
- Periodic DOM scans detect HLS player instances on <video> elements
- Global config object scanning for embedded stream URLs
- Popup queries content script via chrome.tabs.sendMessage for real-time data
- If no DOM videos found but content script has data, create entries from intercepted sources

Changes:
- content.js: Full rewrite with main-world injection + XHR/fetch interception
- index.js: Query content scripts via messages, merge with DOM snapshot
- manifest.json: all_frames + document_start for early injection

manifest.json

@@ -27,7 +27,8 @@
     {
       "matches": ["<all_urls>"],
       "js": ["content.js"],
-      "run_at": "document_idle"
+      "run_at": "document_start",
+      "all_frames": true
     }
   ],
   "icons": {