fix(player): recover a failed stream on Linux instead of stopping (DR-130)

A recoverable player error meant "playback is over": the frontend's error
handler stopped the player unconditionally, so a wifi blip killed the
track. Android already decides in its JNI callback, but MpvBackend is
constructed before PlayerController exists, so its event thread has no
controller to ask.

So MPV reports the failure and the frontend echoes it into the new
player_recover_stream command — the same shape as PlaybackEnded ->
player_on_playback_ended, keeping the decision in Rust. The command
re-opens the stream where it stopped, with the existing attempt budget
and backoff, and returns whether it handled it; only a false answer
falls through to the old stop path.

Android now reports the errors it has already declined as
*unrecoverable*, so the echo never asks the same question twice.

TRACES: UR-004, UR-040 | DR-130 | UT-117

src/lib/services/playerEvents.ts

@@ -276,9 +276,32 @@ async function handlePlaybackEnded(): Promise<void> {
 
 /**
  * Handle error events.
+ *
+ * A recoverable error gets one chance at recovery before anything is torn down.
+ * Backends whose event thread cannot reach the controller (MpvBackend is built
+ * before PlayerController exists) report the failure and rely on this echo to
+ * put the decision back in Rust — the same shape as PlaybackEnded →
+ * playerOnPlaybackEnded. Nothing is decided here: if Rust re-opened the stream
+ * it says so, and stopping the player would kill the playback it just restored.
+ *
+ * TRACES: UR-004, UR-040 | DR-130
  */
 async function handleError(message: string, recoverable: boolean): Promise<void> {
   console.error(`Playback error (recoverable: ${recoverable}): ${message}`);
+
+  if (recoverable) {
+    try {
+      if (await commands.playerRecoverStream()) {
+        console.log("Stream re-opened after a recoverable error - not stopping");
+        return;
+      }
+    } catch (e) {
+      // Fall through to the normal stop: a failed recovery attempt is still an
+      // error, and leaving the player running would strand it mid-failure.
+      console.error("Stream recovery attempt failed:", e);
+    }
+  }
+
   player.setError(message);
 
   // Stop backend player to prevent orphaned playback