Replace custom API reference with Scalar component

Removed the custom ModernApiReference implementation and replaced it with the ScalarApiReference component using @scalar/api-reference-react. Updated dependencies and imports accordingly to leverage the official Scalar API reference UI, ensuring theme consistency and easier maintenance.

Author: 0xFirekeeper

apps/portal/package.json

@@ -10,6 +10,8 @@
     "@radix-ui/react-slot": "^1.2.3",
     "@radix-ui/react-tabs": "^1.1.12",
     "@radix-ui/react-tooltip": "1.2.7",
+    "@scalar/api-reference-react": "^0.7.42",
+    "@scalar/nextjs-api-reference": "^0.8.17",
     "@tanstack/react-query": "5.81.5",
     "@tryghost/content-api": "^1.11.28",
     "class-variance-authority": "^0.7.1",