feat(web-ext): add bundled web extensions infrastructure
Implement support for bundled web extensions:
1. Ad Blocker (@cliqz/adblocker-electron):
- Native ad blocking using EasyList/EasyPrivacy filter lists
- Runtime enable/disable support
- Blocked request counting
- No webRequest API conflicts with other extensions
2. Chrome Extension Manager:
- Load unpacked Chrome extensions from resources/chrome-extensions/
- Enable/disable per extension (persisted in datastore)
- MV2 and MV3 support via Electron's native API
- Ready for bundling Proton Pass
3. Settings UI:
- New "Privacy" section in Settings
- Toggle for Ad Blocker with blocked count stats
- List of bundled extensions with enable/disable toggles
- Attribution section with license info
4. Infrastructure:
- IPC handlers for all operations
- Preload API (api.adblocker, api.chromeExtensions)
- Database table for extension settings
- Cleanup on app quit
Dependencies added (run yarn install):
- @cliqz/adblocker-electron@^1.27.6
- cross-fetch@^4.0.0