Cherry-picked from upstream PR #404 with conflict resolution:
- Replaced flaky TCP-based Calibre wireless with WebSocket-based transfer
- Added OPDS authentication support (username/password in settings)
- Renamed "Calibre Library" to "OPDS Browser" in home menu
- Added UDP discovery for Calibre plugin communication
- Merged user's custom settings (customFontIndex, fallbackFontFamily, pinnedListName)
- Applied vTaskDelay cleanup after task deletion
- Kept existing "Calibre Settings" menu item (skipped KOReader Sync per preference)
Fixes issue #334 (Calibre wireless transfer not working)
bc4edeef26