feat(subsonic): add getStarred and getStarred2 handlers

Both return user's starred artists/albums/songs sorted liked_at DESC.
Cap at 500 entries per category for v1 (Subsonic spec doesn't define
pagination on these endpoints; M3+ can revisit if needed).

internal/subsonic/subsonic.go

@@ -40,6 +40,8 @@ func Mount(r chi.Router, pool *pgxpool.Pool, logger *slog.Logger, cfg Config, ev
 		register(sub, "/scrobble", m.handleScrobble)
 		register(sub, "/star", m.handleStar)
 		register(sub, "/unstar", m.handleUnstar)
+		register(sub, "/getStarred", m.handleGetStarred)
+		register(sub, "/getStarred2", m.handleGetStarred2)
 		register(sub, "/getUser", handleGetUser)
 
 		// Subsonic clients expect every /rest/* miss to come back as a