MusicThing 0.2.1 — Spotify song-label updates

Fix the bottom Spotify song title remaining at “Loading Song Name” when artwork is already locally proxied. Skip only the redundant artwork rewrite and continue updating title, artist and playback state.

Includes modern and legacy client handlers and regression coverage. All 82 automated checks pass. Reinitialize MusicThing and push/restart the staged client to apply to an existing installation.