Enhance user management, improve API structure, add database optimizations, and update Docker setup

- Introduced endpoints for user management, including CRUD operations, pagination, and password management.
- Added new schema validations for user updates, password strength, pagination, and standardized error responses.
- Integrated custom exception handling for a consistent API error experience.
- Refined CORS settings: restricted methods and allowed headers, added header exposure, and preflight caching.
- Optimized database: added indexes on `is_active` and `is_superuser` fields, updated column types, enforced constraints, and set defaults.
- Updated `Dockerfile` to improve security by using a non-root user and adding a health check for the application.
- Enhanced tests for database initialization, user operations, and exception handling to ensure better coverage.

backend/app/api/main.py

@@ -1,6 +1,7 @@
 from fastapi import APIRouter
 
-from app.api.routes import auth
+from app.api.routes import auth, users
 
 api_router = APIRouter()
-api_router.include_router(auth.router, prefix="/auth", tags=["auth"])
+api_router.include_router(auth.router, prefix="/auth", tags=["Authentication"])
+api_router.include_router(users.router, prefix="/users", tags=["Users"])