Update README for stream offline

README.md

@@ -110,6 +110,17 @@ song has several Genius entries.
 For a live stream the seek bar is replaced by a **LIVE** badge and an elapsed
 counter, since seeking a live stream isn't meaningful.
 
+### Offline fallback
+
+When the now-playing provider reports the stream is offline, the player shows a
+distinct placeholder (`OFFLINE_ART`, default `assets/img/offline.svg`) and an
+"off air" label (`OFFLINE_NAME` / `OFFLINE_MESSAGE`), and the green LIVE dot
+disappears. If you set `OFFLINE_STREAM_URL` to a local/hosted audio file, the
+player switches to it (looped by default via `OFFLINE_LOOP`) so pressing play
+gives listeners a "we'll be right back" bed instead of silence. When the live
+stream returns, the player switches back automatically — without interrupting a
+listener who is already playing.
+
 You can hard-code artwork for specific tracks by creating `config/overrides.json`:
 
 ```json