feat: Gemini AI (doc OCR + face match) + role-assignment endpoints

- GeminiService (integrations/gemini, @Global): extractDocument (OCR fields) + faceMatch; graceful if no GEMINI_API_KEY
- documents: face-match now real via Gemini; POST /admin/documents/:id/ocr extracts fields for CS auto-fill
- roles: PATCH /admin/users/:id/role (admin) + POST /platform/users/role (bootstrap via x-platform-secret)
- config: gemini + platform.secret; .env.example entries

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/driver/lib/controller/auth/facebook_login.dart

@@ -0,0 +1,30 @@
+// import 'package:firebase_auth/firebase_auth.dart';
+// import 'package:flutter_facebook_auth/flutter_facebook_auth.dart';
+
+// class FacebookSignIn {
+//   Future<UserCredential?> signInWithFacebook() async {
+//     final LoginResult result = await FacebookAuth.instance.login();
+//     if (result.status == LoginStatus.success) {
+//       // Create a credential from the access token
+//       final OAuthCredential credential =
+//           FacebookAuthProvider.credential(result.accessToken!.tokenString);
+//       // Once signed in, return the UserCredential
+//       return await FirebaseAuth.instance.signInWithCredential(credential);
+//     }
+//     return null;
+//   }
+
+//   Future<void> signOut() async {
+//     try {
+//       await FacebookAuth.instance.logOut();
+//       print('Facebook Sign Out Successful');
+//     } catch (e) {
+//       print('Error during Facebook Sign Out: $e');
+//     }
+//   }
+
+//   Future<bool> isSignedIn() async {
+//     final accessToken = await FacebookAuth.instance.accessToken;
+//     return accessToken != null;
+//   }
+// }