feat: add include_granted_scopes to Google OAuth

Enables incremental authorization so previously granted scopes
are preserved when requesting new permissions.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/Http/Controllers/Auth/YouTubeController.php

@@ -297,6 +297,7 @@ private function redirectToGoogle(): Response
                 ->with([
                     'access_type' => 'offline',
                     'prompt' => 'consent',
+                    'include_granted_scopes' => 'true',
                 ])
                 ->redirect()
                 ->getTargetUrl()