[TASK] Backend: Implement user authentication database schema and core API endpoints

[sbusso]

Parent Feature

Related to feature #4

Task Description

Create the foundational backend infrastructure for user authentication including database schema, core API endpoints, and basic authentication middleware.

Acceptance Criteria

• User table created with email, password_hash, created_at, updated_at fields
• Database migration scripts for user authentication schema
• POST /api/auth/register endpoint with email/password validation
• POST /api/auth/login endpoint with credential verification
• POST /api/auth/logout endpoint with session invalidation
• Secure password hashing using bcrypt with proper salt rounds
• JWT token generation and validation middleware
• Basic input validation for email format and password strength
• Error handling for duplicate emails and invalid credentials

Implementation Notes

• Use bcrypt with minimum 12 salt rounds for password hashing
• JWT tokens should include user ID and expiration time
• Implement proper HTTP status codes (200, 201, 400, 401, 409, 500)
• Database constraints for unique email addresses
• Environment variables for JWT secret and token expiration

Definition of Done

• Implementation complete with all endpoints functional
• Unit tests written and passing (>90% coverage)
• Integration tests for API endpoints
• Code reviewed and follows security best practices
• Database migrations tested in development environment
• API documentation updated with endpoint specifications

Dependencies

• Database connection and migration system setup
• Environment configuration for JWT secrets
• Password hashing library integration (bcrypt)

Area

Backend

Estimated Effort

Large: 3-5 days