fix(desktop): allow HTML5 video fullscreen through permission handlers

The custom setPermissionCheckHandler only allowed media/audioCapture/
videoCapture, which made Electron deny the 'automatic-fullscreen'
permission consulted during HTML5 video requestFullscreen(). The
request handler's isMediaCapturePermission() also returned false for
'fullscreen'. Result: the native fullscreen button on <video controls>
in chat silently did nothing.

Allow 'fullscreen' + 'automatic-fullscreen' in both handlers.

Verified with a minimal Electron repro using Hermes' exact handlers:
requestFullscreen() failed with 'TypeError: Permissions check failed'
before; works after. User-verified in the packaged desktop app.

apps/desktop/electron/main.ts

@@ -7369,6 +7369,13 @@ function installContextMenuBridge(window: BrowserWindow) {
 // usage strings), so the user keeps a real allow/deny and can revoke it in
 // System Settings afterwards.
 function isMediaCapturePermission(permission, details) {
+  // HTML5 video/audio fullscreen asks the request handler for 'fullscreen'
+  // and the check handler for 'automatic-fullscreen'. Both must be allowed
+  // or the native fullscreen button on <video controls> does nothing.
+  if (permission === 'fullscreen' || permission === 'automatic-fullscreen') {
+    return true
+  }
+
   if (permission === 'audioCapture' || permission === 'videoCapture') {
     return true
   }
@@ -7431,6 +7438,7 @@ function installMediaPermissions() {
   session.defaultSession.setPermissionCheckHandler((_webContents, permission) => {
     return (
       permission === 'media' ||
+      permission === 'automatic-fullscreen' ||
       permission === ('audioCapture' as any) /* todo: is this needed? */ ||
       permission === ('videoCapture' as any)
     )