Add contributor leaderboard

Add types, hook, UI components, and integration for leaderboard showing top users with badges

src/pages/AdminDatabaseStats.tsx

@@ -7,6 +7,7 @@ import { DataQualityOverview } from '@/components/admin/database-stats/DataQuali
 import { GrowthTrendsChart } from '@/components/admin/database-stats/GrowthTrendsChart';
 import { EntityComparisonDashboard } from '@/components/admin/database-stats/EntityComparisonDashboard';
 import { DatabaseHealthDashboard } from '@/components/admin/database-stats/DatabaseHealthDashboard';
+import { ContributorLeaderboard } from '@/components/contributors/ContributorLeaderboard';
 import { useAdminDatabaseStats } from '@/hooks/useAdminDatabaseStats';
 import { useRecentAdditions } from '@/hooks/useRecentAdditions';
 import { Alert, AlertDescription } from '@/components/ui/alert';
@@ -68,26 +69,30 @@ export default function AdminDatabaseStats() {
         </div>
 
         <Tabs defaultValue="overview" className="space-y-6">
-          <TabsList className="grid w-full grid-cols-5">
+          <TabsList className="grid w-full grid-cols-6">
             <TabsTrigger value="overview" className="flex items-center gap-2">
               <Box className="h-4 w-4" />
               Overview
             </TabsTrigger>
             <TabsTrigger value="growth" className="flex items-center gap-2">
               <TrendingUp className="h-4 w-4" />
-              Growth Trends
+              Growth
             </TabsTrigger>
             <TabsTrigger value="comparisons" className="flex items-center gap-2">
               <BarChart3 className="h-4 w-4" />
               Comparisons
             </TabsTrigger>
+            <TabsTrigger value="contributors" className="flex items-center gap-2">
+              <Users className="h-4 w-4" />
+              Contributors
+            </TabsTrigger>
             <TabsTrigger value="quality" className="flex items-center gap-2">
               <Activity className="h-4 w-4" />
-              Data Quality
+              Quality
             </TabsTrigger>
             <TabsTrigger value="health" className="flex items-center gap-2">
               <Shield className="h-4 w-4" />
-              Health Checks
+              Health
             </TabsTrigger>
           </TabsList>
 
@@ -201,6 +206,11 @@ export default function AdminDatabaseStats() {
             <EntityComparisonDashboard />
           </TabsContent>
 
+          {/* Contributors Tab */}
+          <TabsContent value="contributors" className="space-y-6">
+            <ContributorLeaderboard />
+          </TabsContent>
+
           {/* Data Quality Tab */}
           <TabsContent value="quality" className="space-y-6">
             <DataQualityOverview />