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/components/admin/database-stats/DatabaseStatsCard.tsx

@@ -0,0 +1,45 @@
+import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
+import { LucideIcon } from 'lucide-react';
+import { cn } from '@/lib/utils';
+
+interface DatabaseStatsCardProps {
+  title: string;
+  icon: LucideIcon;
+  stats: Array<{
+    label: string;
+    value: number | string;
+    trend?: {
+      value: number;
+      period: string;
+    };
+  }>;
+  iconClassName?: string;
+}
+
+export function DatabaseStatsCard({ title, icon: Icon, stats, iconClassName }: DatabaseStatsCardProps) {
+  return (
+    <Card>
+      <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
+        <CardTitle className="text-sm font-medium">{title}</CardTitle>
+        <Icon className={cn("h-4 w-4 text-muted-foreground", iconClassName)} />
+      </CardHeader>
+      <CardContent>
+        <div className="space-y-2">
+          {stats.map((stat, index) => (
+            <div key={index} className="flex items-center justify-between">
+              <span className="text-sm text-muted-foreground">{stat.label}</span>
+              <div className="flex items-center gap-2">
+                <span className="text-sm font-semibold">{stat.value.toLocaleString()}</span>
+                {stat.trend && (
+                  <span className="text-xs text-muted-foreground">
+                    +{stat.trend.value} ({stat.trend.period})
+                  </span>
+                )}
+              </div>
+            </div>
+          ))}
+        </div>
+      </CardContent>
+    </Card>
+  );
+}