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

package.json

@@ -19,6 +19,7 @@
     "next": "16.1.1",
     "react": "19.2.3",
     "react-dom": "19.2.3",
+    "recharts": "^3.6.0",
     "stripe": "^20.1.2",
     "tailwind-merge": "^3.4.0"
   },