fix(android): drainingTts identity check, mark stopped on WebSocket failure

- Codex P2: drain coroutine now only clears drainingTts if it's the
  same instance (=== check), preventing a newer drain from being
  unreachable by stopTts.
- Codex P2: set stopped=true on WebSocket onFailure so subsequent
  sendText calls are rejected and stale state doesn't persist.

apps/android/app/src/main/java/ai/openclaw/android/voice/ElevenLabsStreamingTts.kt

@@ -178,6 +178,7 @@ class ElevenLabsStreamingTts(
 
       override fun onFailure(webSocket: WebSocket, t: Throwable, response: Response?) {
         Log.e(TAG, "WebSocket error: ${t.message}")
+        stopped = true
         cleanup()
       }