Fix ffmpeg spawn failure causing infinite retry loop

Two issues fixed:
1. Cross-platform ffmpeg-static resolution: skip Windows .exe paths on Linux
   and always fall back to "ffmpeg" instead of a known-bad path
2. Prevent trackEnd cascade when ffmpeg spawn fails — track consecutive
   failures and stop after 3, suppressing trackEnd on spawn errors

https://claude.ai/code/session_013vHRF8BbDGjZLqheFS85Q6

src/bot/instance.ts

@@ -263,6 +263,8 @@ export class BotInstance extends EventEmitter {
     this.queue.add({ ...song, platform: provider.platform });
     this.queue.play();
 
+    // Reset failure counter on user-initiated play
+    this.player.resetFailures();
     const ok = await this.resolveAndPlay(this.queue.current()!);
     if (!ok) return `Cannot play: ${song.name}`;
     return `Now playing: ${song.name} - ${song.artist}`;