chore: pre-release cleanup

- Remove dead chatgpt.js (unused — all auth flows go through signup-page.js)
- Remove chatgpt.com from manifest content_scripts
- Fix resetState() to preserve vpsUrl and mailProvider on manual reset
- Add 30s timeout to all tabs.onUpdated listeners (prevent hanging)
- Fix misleading "All runs finished" log when loop breaks early
- Remove stale TODO comment in signup-page.js
- Add disabled styles for .btn-primary and .run-count-input
- Remove unused `indicator` variable in sidepanel.js
- Fix trailing comma in manifest.json

manifest.json

@@ -46,11 +46,6 @@
       "js": ["content/utils.js", "content/mail-163.js"],
       "all_frames": true,
       "run_at": "document_idle"
-    },
-    {
-      "matches": ["https://chatgpt.com/*"],
-      "js": ["content/utils.js", "content/chatgpt.js"],
-      "run_at": "document_idle"
     }
   ],
   "action": {