feat(immersive): replace Credits panel with Track Info panel

- Create TrackInfoPanel with full track metadata and credits
- Display: duration, quality, ISRC, label, and all performer credits
- Uses same backend as TrackInfoModal (get_track_info command)
- Rename tab from 'Credits' to 'Track Info' (player.trackInfo)
- Update keyboard shortcut from 'C' to 'T' for Track Info tab
- Fix actions.clearQueue -> player.clearQueue translation key
- Add i18n translations for trackInfo in EN/ES
- Delete old placeholder CreditsPanel

src/lib/i18n/locales/en.json

@@ -254,6 +254,7 @@
     "noLyrics": "No lyrics available",
     "fetchingLyrics": "Fetching lyrics...",
     "credits": "Credits",
+    "trackInfo": "Track Info",
     "suggestions": "Suggestions",
     "shuffle": "Shuffle",
     "repeat": "Repeat",