Add login system and security features to the admin panel

Implement a secure login system with CSRF protection and update documentation to reflect new security features and project structure.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 4163c44a-913d-44be-abd1-cc73fd26d1a7
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Event-Id: 89639d73-47b9-47e2-a7bd-f131cedd4747
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/9181f32a-0206-49f3-a282-cf7ea18d1e68/4163c44a-913d-44be-abd1-cc73fd26d1a7/DYd9AEs
