feat: add Gemini AI tracking and fix admin dashboard

- Integrated API tracking into analyze-bottle service
- Added credit balance check before Gemini API calls
- Deduct credits after successful Gemini analysis
- Track both successful and failed Gemini API calls
- Added debug logging to admin dashboard for recent API calls
- Fixed error handling in analyze-bottle

Now tracks both Google Search and Gemini AI API usage!

src/app/admin/page.tsx

@@ -30,7 +30,8 @@ export default async function AdminPage() {
     const stats = await getGlobalApiStats();
 
     // Fetch recent API usage
-    const { data: recentUsage } = await supabase
+    console.log('[Admin Page] Fetching recent API usage...');
+    const { data: recentUsage, error: recentError } = await supabase
         .from('api_usage')
         .select(`
             *,
@@ -41,6 +42,8 @@ export default async function AdminPage() {
         .order('created_at', { ascending: false })
         .limit(50);
 
+    console.log('[Admin Page] Recent usage - count:', recentUsage?.length, 'error:', recentError);
+
     // Fetch per-user statistics
     const { data: userStats } = await supabase
         .from('api_usage')