fix: stabilize IPTV playback and implement request throttling

- Add playback lock to XtreamService to delay EPG during stream init
- Increase MPEG-TS stash buffer to 512KB for better stability
- Enable liveBufferLatencyChasing to prevent stream drift
- Tune HLS parameters for balanced speed and reliability

web/player.html

@@ -253,15 +253,15 @@
             const isTurbo = urlParams.get('turbo') === 'true';
 
             const hls = new Hls({
-                maxBufferLength: isTurbo ? 30 : 45,
+                maxBufferLength: isTurbo ? 45 : 50,
                 enableWorker: true,
-                liveSyncDurationCount: isTurbo ? 2 : 4,
+                liveSyncDurationCount: isTurbo ? 3 : 4, // Improved stability
                 // Turbo-Start specific
                 startLevel: isTurbo ? 0 : -1,
                 initialLiveManifestSize: 1,
                 abrEwmaDefaultEstimate: 500000,
-                manifestLoadingRetryDelay: 500,
-                levelLoadingRetryDelay: 500
+                manifestLoadingRetryDelay: 800,
+                levelLoadingRetryDelay: 800
             });
             window.hlsInstance = hls;
             hls.loadSource(url);