Refactor Media Manager log to use streaming and card UI

- **UI Overhaul**: Moved the activity log to a dedicated, expandable card at the bottom of the Media Manager modal.
- **Styling**: Updated the log card to match the application's light theme using CSS variables (`--surface`, `--text`).
- **Log Streaming**: Replaced batch logging with real-time streaming via `CacheService` and `pollJobLogs`.
- **Session Resumption**: Implemented logic to resume log polling for active jobs upon page reload.
- **Fixes**:
    - Exposed `pollJobLogs` in `global.ts` to fix "Script function not found" error.
    - Updated `mediaHandlers.test.ts` with `CacheService` mocks and new signatures.
    - Removed legacy auto-hide/toggle logic for the log.