Add comprehensive test suite and utilities for user functionality

This commit introduces a suite of tests for user models, schemas, CRUD operations, and authentication services. It also adds utilities for in-memory database setup to support these tests and updates environment settings for consistency.

backend/app/models/__init__.py

@@ -0,0 +1,14 @@
+"""
+Models package initialization.
+Imports all models to ensure they're registered with SQLAlchemy.
+"""
+# First import Base to avoid circular imports
+from app.core.database import Base
+from .base import TimestampMixin, UUIDMixin
+
+# Import user model
+from .user import User
+__all__ = [
+    'Base', 'TimestampMixin', 'UUIDMixin',
+    'User',
+]

backend/app/models/base.py

@@ -0,0 +1,20 @@
+import uuid
+from datetime import datetime, timezone
+
+from sqlalchemy import Column, DateTime
+from sqlalchemy.dialects.postgresql import UUID
+
+# noinspection PyUnresolvedReferences
+from app.core.database import Base
+
+
+class TimestampMixin:
+    """Mixin to add created_at and updated_at timestamps to models"""
+    created_at = Column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc), nullable=False)
+    updated_at = Column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc),
+                        onupdate=lambda: datetime.now(timezone.utc), nullable=False)
+
+
+class UUIDMixin:
+    """Mixin to add UUID primary keys to models"""
+    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)

backend/app/models/user.py

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+from sqlalchemy import Column, String, JSON, Boolean
+
+from .base import Base, TimestampMixin, UUIDMixin
+
+
+class User(Base, UUIDMixin, TimestampMixin):
+    __tablename__ = 'users'
+
+    email = Column(String, unique=True, nullable=False, index=True)
+    password_hash = Column(String, nullable=False)
+    first_name = Column(String, nullable=False, default="user")
+    last_name = Column(String, nullable=True)
+    phone_number = Column(String)
+    is_active = Column(Boolean, default=True, nullable=False)
+    is_superuser = Column(Boolean, default=False, nullable=False)
+    preferences = Column(JSON)
+
+    def __repr__(self):
+        return f"<User {self.email}>"