Spotify follows source mode, name and credentials live

- spotify_init() sets up the logger, zeroconf routes and session task
  once; spotify_apply() (at boot and on every source save) enables or
  disables: enabled = mode spotify/auto + credentials. Disable removes
  the mDNS entry, zeroconf answers 404 and a running session ends
  (loop exits within 200 ms, SpircHandler::disconnect stops the queue
  and player tasks). A new device name ends the session and
  re-advertises. The login blob is swapped under a mutex.
- Verified: hls/spotify/rename switch the mDNS entry and /spotify_info
  (404/200) live; switching to hls during Spotify playback ended the
  session in < 2 s, HLS played after ~5 s, internal heap 221 -> 365 KB
  (cspot frees everything).
- CLAUDE.md: OTA-with-session findings (intermittent, flash-write stalls
  seen as TX resyncs during uploads), serial-port reset caveat.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

main/player.c

@@ -95,6 +95,9 @@ static size_t player_read(int32_t *buf, size_t frames)
 
 void player_apply(const cJSON *source)
 {
+    if (s_spotify_conv) {       // after player_init: Spotify follows mode / name / credentials live
+        spotify_apply();
+    }
     player_src_t src = mode_of(cJSON_GetObjectItemCaseSensitive(source, "mode")->valuestring);
     if (src == s_src) {
         return;