Fix production environment variables

- Remove old Confluence variables
- Add NEXT_PUBLIC_API_URL for API access

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.env.production

@@ -1,5 +1,3 @@
 # This file is for Amplify to know which env vars to expose to Next.js
 # The actual values come from Amplify Environment Variables
-CONFLUENCE_API_URL=${CONFLUENCE_API_URL}
-CONFLUENCE_TOKEN=${CONFLUENCE_TOKEN}
-CONFLUENCE_PAGE_ID=${CONFLUENCE_PAGE_ID}
+NEXT_PUBLIC_API_URL=${NEXT_PUBLIC_API_URL}