- Added source toggle UI in `components/video-modal.html`.
- Updated `VideoModal.js` to manage toggle visibility (only when both URL and Magnet exist), update peer/server counts, and dispatch `playback:switch-source` events.
- Updated `PlaybackService.js` to support a `forcedSource` option, allowing bypassing of the URL probe when "torrent" is forced.
- Updated `app.js` to listen for the toggle event and re-initialize playback with the forced source preference.
- Updated `tests/ui/helpers/jsdom-test-helpers.mjs` to expose necessary globals for JSDOM testing.
- Verified functionality with targeted updates and existing unit tests.