feat: Implement automatic updated_at timestamp management in BaseModel and update BaseRepository to reflect changes

app/models/base.py

@@ -1,5 +1,6 @@
 from datetime import UTC, datetime
 
+from sqlalchemy import event
 from sqlmodel import Field, SQLModel
 
 
@@ -11,3 +12,10 @@ class BaseModel(SQLModel):
     # timestamps
     created_at: datetime = Field(default_factory=lambda: datetime.now(UTC))
     updated_at: datetime = Field(default_factory=lambda: datetime.now(UTC))
+
+
+# SQLAlchemy event listener to automatically update updated_at timestamp
+@event.listens_for(BaseModel, "before_update", propagate=True)
+def update_timestamp(mapper, connection, target):
+    """Automatically set updated_at timestamp before update operations."""
+    target.updated_at = datetime.now(UTC)