fix(gateway): crash safety on screen-share input timeout + proper error serialization

Root cause of "langsung left": YouTube bot-block/403 on u_c1tRmj7E4 (live
stream, LOGIN_REQUIRED) made yt-dlp timeout in resolveInputWithRetry (12s).
The timeout handler did cleanup() (removing once() listeners) THEN
tee.destroy(new Error(...)) — the PassThrough emitted 'error' with NO
listener left → unhandled stream 'error' event → uncaughtException →
gracefulShutdown → bot left voice.

Fix:
- resolveInputWithRetry: tee.destroy() silently after cleanup (error carried
  in the rejection only); add permanent no-op tee.on('error') safety.
- prepareStream: output.on('error') no-op so ffmpeg spawn failure before
  playStream attaches a demux listener never crashes the gateway.
- bootstrap: serialize uncaughtException/ClientError/DB errors with
  {err, errorMsg, stack} (pino only serializes the 'err' magic key — the old
  {error: err} key printed {} so crashes were invisible).

services/discord-gateway/src/modules/voice-recording/screenShareController.ts

@@ -93,11 +93,11 @@ export class ScreenShareController {
           const timer = setTimeout(() => {
             cleanup();
             destroyInput();
-            tee.destroy(
-              new Error(
-                "Screen input produced no data within 12s — merge likely failed",
-              ),
-            );
+            // Listeners were just removed by cleanup() — destroying tee WITH
+            // an error would emit "error" on an unlistened PassThrough and
+            // surface as an unhandled 'error' event (crash). Destroy
+            // silently; the error lives in the rejection only.
+            tee.destroy();
             reject(
               new Error(
                 "Screen input produced no data within 12s — merge likely failed",
@@ -131,6 +131,11 @@ export class ScreenShareController {
           tee.once("end", onEnd);
         });
 
+        // Safety net: cleanup() removes the once() listeners on timeout/error,
+        // but a late error event from input.pipe(tee) can still fire on an
+        // unlistened PassThrough and crash the gateway (unhandled 'error').
+        // A permanent no-op listener guarantees the event is always swallowed.
+        tee.on("error", () => {});
         // Pass the tee onward — the encoder consumes the same buffered
         // stream, so no data from the merge is lost.
         return tee;