feat: implement api crud for auth pages and email

[ngovinh2k2]

What?

Implement API crud for auth pages and email

Why?

How?

Testing?

• Functional Testing
• Security
• Performance
• Error Handling
• Code Quality
• Documentation
• Database
• Deployment
• Final Review

Anything Else?

[gemini-code-assist]

Code Review

This pull request introduces a new custom_page Django application to manage custom pages (such as sign-in, sign-up, and password reset pages) for organizations. It includes the database model, serializers, default page services, migrations to backfill existing organizations, and an API endpoint to list these pages. The feedback highlights a critical improvement opportunity: adding a unique constraint on the combination of organization and page_type in the CustomPage model to prevent duplicate pages of the same type for a single organization.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.