feat: Implement complete JWT authentication system with security feat…

[Skinny001]

✨ Authentication Features:

• JWT access tokens (15min expiry) with auto-refresh
• Refresh tokens (7 days) with automatic rotation
• Device fingerprinting for enhanced security
• Account lockout after 5 failed login attempts
• Secure password hashing with bcrypt (12 rounds)
• Complete session management

🔐 Backend Implementation:

• AuthService with full authentication logic
• 7 REST endpoints: register, login, refresh, logout, verify-email, forgot-password, reset-password
• Security entities: RefreshToken, Session, FailedLoginAttempt
• Device fingerprint utilities and validation
• Comprehensive error handling and validation

🎨 Frontend Integration:

• AuthContext with state management
• Protected routes with automatic redirects
• Auto-refresh tokens every 13 minutes
• Login, register, forgot password, and reset password pages
• Dashboard and session management UI

📚 Documentation & Testing:

• Comprehensive implementation guide
• Testing scripts and verification checklist
• API endpoint documentation
• Security configuration guide

🔧 Technical Details:

• TypeScript implementation throughout
• NestJS backend with TypeORM
• Next.js frontend with React Context
• JWT token rotation for security
• Input validation and sanitization
• Enterprise-ready authentication flow

close #49