feat: implement merchant dashboard, secure auth, and short_id system

- Added dedicated merchant dashboard with analytics and transactions
- Implemented API Key based authentication for merchants
- Introduced 8-character Short IDs for merchants to use in URLs
- Refactored checkout and payment intent APIs to support multi-gateway
- Enhanced Landing Page with Merchant Portal access and marketing copy
- Fixed Next.js 15 async params build issues
- Updated internal branding to P2CGateway
- Added AyrisTech credits to footer

lib/supabase-admin.ts

@@ -0,0 +1,9 @@
+import { createClient } from '@supabase/supabase-js';
+
+const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL!;
+
+// This should ONLY be used in Server Components or API Routes
+export const supabaseAdmin = createClient(
+    supabaseUrl,
+    process.env.SUPABASE_SERVICE_ROLE_KEY!
+);