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/rider/lib/homw_widget.dart

@@ -0,0 +1,18 @@
+import 'package:flutter/services.dart';
+
+class WidgetManager {
+  static const platform = MethodChannel('com.mobileapp.store.ride/widget');
+
+  static Future<void> updateWidget() async {
+    try {
+      await platform.invokeMethod('updateWidget');
+    } on PlatformException catch (e) {
+      print("Failed to update widget: '${e.message}'.");
+    }
+  }
+}
+
+// Example usage:
+void updateHomeScreenWidget() {
+  WidgetManager.updateWidget();
+}