Feat/add user models

[RokuSennyou]

This pull request introduces a custom user model and profile system, integrates JWT-based authentication, and adds API endpoints for user registration, login, profile retrieval, and token refresh. It also updates admin management and documentation to support these changes, ensuring both backend and frontend developers have clear guidance.

Authentication and User Model Integration

• Implemented a custom User model with UUID primary key, unique email, real name, and identity field (student/teacher/admin), along with a related UserProfile model for additional user info such as student_id, bio, and avatar. [1] [2]
• Configured Django settings to use the custom user model (AUTH_USER_MODEL), enabled JWT authentication with rest_framework_simplejwt, and set up media file handling for avatar uploads. [1] [2]

API Endpoints and Serializers

• Added API endpoints for user registration (/auth/signup/), login (/auth/session/), token refresh (/auth/refresh), and profile retrieval (/auth/me), with corresponding serializers for input validation and response formatting. [1] [2] [3]

Admin and Signals

• Enhanced Django admin with custom management for User and UserProfile, and implemented a signal to automatically create a profile when a user is registered. [1] [2] [3]

Documentation Updates

• Added a comprehensive frontend API documentation (docs/frontend.MD) detailing authentication endpoints, request/response formats, error messages, and usage examples for frontend integration.
• Updated the main README.md to clarify documentation for backend and frontend developers.

[Copilot]

Pull Request Overview

This PR introduces a comprehensive user authentication system to the Django backend, implementing JWT-based authentication with custom user models and API endpoints for frontend integration.

• Implements a custom User model with UUID primary key, unique email, and identity field (teacher/admin/student)
• Adds JWT-based authentication with registration, login, profile retrieval, and token refresh endpoints
• Includes comprehensive API documentation for frontend developers

Reviewed Changes

Copilot reviewed 12 out of 15 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
user/models.py	Defines custom User and UserProfile models with UUID primary key and identity fields
user/views.py	Implements API views for user registration and profile retrieval
user/serializers.py	Creates serializers for registration and user profile data handling
user/urls.py	Configures URL patterns for authentication endpoints
user/signals.py	Implements signal to auto-create user profiles
user/admin.py	Customizes Django admin interface for User and UserProfile management
back_end/settings.py	Configures JWT authentication and custom user model
back_end/urls.py	Includes user authentication URLs and media file serving
docs/frontend.MD	Provides comprehensive API documentation for frontend developers
README.md	Updates documentation links for backend and frontend developers

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[Copilot]

The refresh endpoint URL is inconsistent with the documentation. The URL pattern uses 'refresh/' but the documentation references '/auth/refresh' (without trailing slash). Consider adding a trailing slash for consistency.

Suggested change

	path('refresh/', TokenRefreshView.as_view(), name='token_refresh'),
	path('auth/refresh/', TokenRefreshView.as_view(), name='token_refresh'),