Linthra 0.1.2 — unified multi-source library & smarter playback.

Added:
- Tracks available from more than one source (local files, Jellyfin, and
  Subsonic/Navidrome) are now unified into a single library entry instead of
  appearing as duplicates.
- A default playback source setting, so you can choose which provider a
  unified track plays from.
- Smarter playback source selection, with automatic fallback to another
  source at runtime when the preferred one can't play.

Changed:
- Clearer Subsonic/Navidrome connection error messages.

Fixed:
- Artwork now falls back per provider, and duplicate matching is more
  conservative so distinct tracks are no longer merged by mistake.

No ads, no tracking, no analytics, no telemetry.
