chore(root): remove DRF stack and update configuration

This change removes unused DRF-related dependencies, updates .env.sample and .gitignore to reflect new configuration, and adds a comprehensive project architecture plan (PLAN.md). It simplifies the stack and prepares the codebase for a modular, permission‑driven design.

New Features
- Added detailed PLAN.md outlining project structure, apps, permissions, and tech stack.
Enhancements
- Cleaned up .env.sample by removing obsolete environment variables.
- Updated .gitignore to exclude generated directories and track migrations properly.
Bug Fixes
- No bug fixes included in this commit.

.env.sample

@@ -1,19 +1,13 @@
-# Django settings
 DJANGO_SETTINGS_MODULE=config.settings.development
 SECRET_KEY=your-secret-key
 ALLOWED_HOSTS=api.your-domain.com,www.your-domain.com
 
-# Database URL (recommended for production)
 DATABASE_URL=postgres://user:password@localhost:5432/config
 
-# Frontend URL
-FRONTEND_URL=https://frontend.your-domain.com,www.frontend.your-domain.com
-
-# Email settings
 EMAIL_HOST=
 EMAIL_PORT=
 EMAIL_USE_TLS=
 EMAIL_HOST_USER=
 EMAIL_HOST_PASSWORD=
 DEFAULT_FROM_EMAIL=
-SERVER_EMAIL=
+SERVER_EMAIL=