feat: implement complete CMT backend with API endpoints and test suite

- Add 7 core API endpoints: users, transactions, partners, products, inventory, payments, credit
- Implement role-based authentication (admin/write/read-only access)
- Add comprehensive database models with proper relationships
- Include full test coverage for all endpoints and business logic
- Set up Alembic migrations and Docker configuration
- Configure FastAPI app with CORS and database integration

backend/tests/core/test_auth.py

@@ -0,0 +1,22 @@
+import pytest
+from app.core.auth import get_password_hash, verify_password, create_access_token
+from app.schemas.base import UserRole
+
+
+def test_password_hashing():
+    """Test password hashing and verification."""
+    password = "testpassword123"
+    hashed = get_password_hash(password)
+    
+    assert hashed != password
+    assert verify_password(password, hashed) is True
+    assert verify_password("wrongpassword", hashed) is False
+
+
+def test_create_access_token():
+    """Test JWT token creation."""
+    data = {"sub": "testuser", "user_id": 1, "role": UserRole.ADMIN}
+    token = create_access_token(data, expires_delta=None)
+    
+    assert isinstance(token, str)
+    assert len(token) > 0