selfbot streaming: verified live; capture via system ffmpeg x11grab

End-to-end verified with a real burner token + voice channel: login OK, posts
to the text channel, joins voice, and Go-Live streams the host :1 desktop.

- selfbot.ts now captures the X display with the SYSTEM ffmpeg (reliable
  x11grab) and pipes it into prepareStream, instead of relying on the lib's
  bundled libav input devices (not portable). Capture process is killed on stop.
- package.json: trustedDependencies (node-av, @lng2004/node-datachannel) so the
  native streaming deps build automatically on bun install (incl. Docker).
- Dropped the unused nvenc path (the lib's exported `nvenc` is undefined at
  runtime); software H264 encode for now.

bot/package.json

@@ -27,5 +27,9 @@
     "@types/node": "^22.7.0",
     "@types/qrcode": "^1.5.6",
     "typescript": "^5.6.3"
-  }
+  },
+  "trustedDependencies": [
+    "@lng2004/node-datachannel",
+    "node-av"
+  ]
 }