Implement admin database stats dashboard

Add admin-only database statistics dashboard
- Introduces types for database statistics and recent additions
- Implements hooks to fetch statistics and recent additions via RPCs
- Adds UI components for stats cards and a recent additions table
- Integrates new AdminDatabaseStats page and routing under /admin/database-stats
- Updates admin sidebar and app routes to expose the new dashboard
- Enables real-time updates and export capabilities for recent additions

src/types/database-stats.ts

@@ -0,0 +1,62 @@
+export interface DatabaseStatistics {
+  parks: {
+    total: number;
+    active: number;
+    historical: number;
+    added_7d: number;
+    added_30d: number;
+  };
+  rides: {
+    total: number;
+    active: number;
+    historical: number;
+    added_7d: number;
+    added_30d: number;
+  };
+  companies: {
+    total: number;
+    manufacturers: number;
+    operators: number;
+    designers: number;
+    added_7d: number;
+    added_30d: number;
+  };
+  ride_models: {
+    total: number;
+    added_7d: number;
+    added_30d: number;
+  };
+  locations: {
+    total: number;
+  };
+  timeline_events: {
+    total: number;
+  };
+  photos: {
+    total: number;
+    added_7d: number;
+    added_30d: number;
+  };
+  users: {
+    total: number;
+    active_30d: number;
+  };
+  submissions: {
+    pending: number;
+    approved: number;
+    rejected: number;
+  };
+}
+
+export interface RecentAddition {
+  entity_id: string;
+  entity_type: 'park' | 'ride' | 'company' | 'ride_model' | 'location' | 'timeline_event' | 'photo';
+  entity_name: string;
+  entity_slug: string | null;
+  park_slug: string | null;
+  image_url: string | null;
+  created_at: string;
+  created_by_id: string | null;
+  created_by_username: string | null;
+  created_by_avatar: string | null;
+}