Fix EINTR crash from pino ThreadStream during FFmpeg playback

The pino logger's ThreadStream was throwing unhandled EINTR errors
when FFmpeg child processes were spawned, crashing the entire bot.
Add an error handler to suppress EINTR and prevent process crashes.

https://claude.ai/code/session_01EjpEsC2GCsvwbu4n3XC8EE

src/logger.ts

@@ -26,5 +26,11 @@ export function createLogger(logDir?: string): Logger {
     ],
   });
 
+  // Prevent EINTR errors from crashing the process (known pino/thread-stream issue on Linux)
+  transport.on("error", (err: Error) => {
+    if ((err as NodeJS.ErrnoException).code === "EINTR") return;
+    console.error("Logger transport error:", err);
+  });
+
   return pino({ level: "debug" }, transport);
 }