refactor: update timestamp handling to use timezone-aware datetime

app/models/user.py

@@ -3,6 +3,7 @@
 import secrets
 from datetime import datetime
 from typing import TYPE_CHECKING, Optional
+from zoneinfo import ZoneInfo
 
 from sqlalchemy import DateTime, ForeignKey, Integer, String
 from sqlalchemy.orm import Mapped, mapped_column, relationship
@@ -63,13 +64,13 @@ class User(db.Model):
     # Timestamps
     created_at: Mapped[datetime] = mapped_column(
         DateTime,
-        default=datetime.utcnow,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
         nullable=False,
     )
     updated_at: Mapped[datetime] = mapped_column(
         DateTime,
-        default=datetime.utcnow,
-        onupdate=datetime.utcnow,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
+        onupdate=lambda: datetime.now(tz=ZoneInfo("UTC")),
         nullable=False,
     )
 
@@ -103,9 +104,11 @@ class User(db.Model):
             "role": self.role,
             "is_active": self.is_active,
             "api_token": self.api_token,
-            "api_token_expires_at": self.api_token_expires_at.isoformat()
-            if self.api_token_expires_at
-            else None,
+            "api_token_expires_at": (
+                self.api_token_expires_at.isoformat()
+                if self.api_token_expires_at
+                else None
+            ),
             "providers": providers,
             "plan": self.plan.to_dict() if self.plan else None,
             "credits": self.credits,
@@ -129,13 +132,13 @@ class User(db.Model):
         self.email = provider_data.get("email", self.email)
         self.name = provider_data.get("name", self.name)
         self.picture = provider_data.get("picture", self.picture)
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
         db.session.commit()
 
     def set_password(self, password: str) -> None:
         """Hash and set user password."""
         self.password_hash = generate_password_hash(password)
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     def check_password(self, password: str) -> bool:
         """Check if provided password matches user's password."""
@@ -151,7 +154,7 @@ class User(db.Model):
         """Generate a new API token for the user."""
         self.api_token = secrets.token_urlsafe(32)
         self.api_token_expires_at = None  # No expiration by default
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
         return self.api_token
 
     def is_api_token_valid(self) -> bool:
@@ -162,23 +165,23 @@ class User(db.Model):
         if self.api_token_expires_at is None:
             return True  # No expiration
 
-        return datetime.utcnow() < self.api_token_expires_at
+        return datetime.now(tz=ZoneInfo("UTC")) < self.api_token_expires_at
 
     def revoke_api_token(self) -> None:
         """Revoke the user's API token."""
         self.api_token = None
         self.api_token_expires_at = None
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     def activate(self) -> None:
         """Activate the user account."""
         self.is_active = True
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     def deactivate(self) -> None:
         """Deactivate the user account."""
         self.is_active = False
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     @classmethod
     def find_by_email(cls, email: str) -> Optional["User"]:
@@ -218,7 +221,7 @@ class User(db.Model):
             oauth_provider.email = email
             oauth_provider.name = name
             oauth_provider.picture = picture
-            oauth_provider.updated_at = datetime.utcnow()
+            oauth_provider.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
             # Update user info with latest data
             user.update_from_provider(