fix mse buffer trim spinning in a remove loop

Subtracting 15s from the buffered end left a floating point remainder, so when Firefox held exactly 15s of buffer the handler called remove() on a near-zero range that removed nothing, and each updateend called it again. The loop pegged a CPU core and kept running after the websocket closed. Trimming now requires more than 1s past the window.

web/src/components/player/MsePlayer.tsx

@@ -473,7 +473,7 @@ function MSEPlayer({
           } else if (sb.buffered && sb.buffered.length) {
             const end = sb.buffered.end(sb.buffered.length - 1) - 15;
             const start = sb.buffered.start(0);
-            if (end > start) {
+            if (end - start > 1) {
               sb.remove(start, end);
               msRef.current?.setLiveSeekableRange(end, end + 15);
             }