feat(cdn): integrate CDN Manager into the application

- Updated environment configurations to include CDN Manager in the RETURN_TO_ALLOWLIST.
- Enhanced target app resolution to recognize CDN-related hosts.
- Added CDN Manager to the application switcher and updated relevant documentation.
- Included tests to verify the correct mapping of CDN hosts.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/api/src/lib/target-app.ts

@@ -51,6 +51,13 @@ export function targetAppFromReturnTo(
   ) {
     return 'dns'
   }
+  if (
+    /\bcdn\b/.test(hay) ||
+    host.includes('cdnmanager') ||
+    host.includes('cdn-manager')
+  ) {
+    return 'cdn'
+  }
   return 'portal'
 }