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/controller/home/decode_polyline_isolate.dart

@@ -0,0 +1,62 @@
+import 'package:google_maps_flutter/google_maps_flutter.dart';
+
+List<LatLng> decodePolylineIsolate(String encoded) {
+  List<LatLng> points = [];
+  int index = 0, len = encoded.length;
+  int lat = 0, lng = 0;
+
+  while (index < len) {
+    int b, shift = 0, result = 0;
+    do {
+      b = encoded.codeUnitAt(index++) - 63;
+      result |= (b & 0x1f) << shift;
+      shift += 5;
+    } while (b >= 0x20);
+    int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
+    lat += dlat;
+
+    shift = 0;
+    result = 0;
+    do {
+      b = encoded.codeUnitAt(index++) - 63;
+      result |= (b & 0x1f) << shift;
+      shift += 5;
+    } while (b >= 0x20);
+    int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
+    lng += dlng;
+
+    points.add(LatLng(lat / 1E5, lng / 1E5));
+  }
+  return points;
+}
+// Helper method for decoding polyline (if not already defined)
+// List<LatLng> decodePolyline(String encoded) {
+//   List<LatLng> points = [];
+//   int index = 0, len = encoded.length;
+//   int lat = 0, lng = 0;
+
+//   while (index < len) {
+//     int b, shift = 0, result = 0;
+//     do {
+//       b = encoded.codeUnitAt(index++) - 63;
+//       result |= (b & 0x1f) << shift;
+//       shift += 5;
+//     } while (b >= 0x20);
+//     int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
+//     lat += dlat;
+
+//     shift = 0;
+//     result = 0;
+//     do {
+//       b = encoded.codeUnitAt(index++) - 63;
+//       result |= (b & 0x1f) << shift;
+//       shift += 5;
+//     } while (b >= 0x20);
+//     int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
+//     lng += dlng;
+
+//     points.add(LatLng(lat / 1E5, lng / 1E5));
+//   }
+
+//   return points;
+// }