```

Rename metadata fields for clarity and fix imports.

Updated metadata-related field names across models to improve clarity and consistency (e.g., `metadata` to `media_metadata` and `notification_metadata`). Fixed an error in `guest_gifts` metadata reference and added a proper imports initialization in `__init__.py` for all models.
```

backend/app/models/activity_log.py

@@ -59,21 +59,21 @@ class ActivityLog(Base, UUIDMixin, TimestampMixin):
     # Request Information
     ip_address = Column(String)
     user_agent = Column(String)
-    
+
     # Additional Data
-    data = Column(JSONB, default=dict)
-    
+    activity_data = Column(JSONB, default=dict)
+
     # Relationships
     event = relationship("Event")
     user = relationship("User", foreign_keys=[user_id])
     guest = relationship("Guest")
-    
+
     def __repr__(self):
         return f"<ActivityLog {self.activity_type.value} event_id={self.event_id}>"
-    
+
     @classmethod
-    def log_event_activity(cls, activity_type, event_id, user_id=None, description=None, 
-                          ip_address=None, user_agent=None, **data):
+    def log_event_activity(cls, activity_type, event_id, user_id=None, description=None,
+                           ip_address=None, user_agent=None, **data):
         """
         Helper method to create an event activity log entry
         """
@@ -84,12 +84,12 @@ class ActivityLog(Base, UUIDMixin, TimestampMixin):
             description=description,
             ip_address=ip_address,
             user_agent=user_agent,
-            data=data
+            activity_data=data
         )
-    
+
     @classmethod
-    def log_user_activity(cls, activity_type, user_id, event_id=None, description=None, 
-                         ip_address=None, user_agent=None, **data):
+    def log_user_activity(cls, activity_type, user_id, event_id=None, description=None,
+                          ip_address=None, user_agent=None, **data):
         """
         Helper method to create a user activity log entry
         """
@@ -100,12 +100,12 @@ class ActivityLog(Base, UUIDMixin, TimestampMixin):
             description=description,
             ip_address=ip_address,
             user_agent=user_agent,
-            data=data
+            activity_data=data
         )
-    
+
     @classmethod
-    def log_guest_activity(cls, activity_type, guest_id, event_id, description=None, 
-                          ip_address=None, user_agent=None, **data):
+    def log_guest_activity(cls, activity_type, guest_id, event_id, description=None,
+                           ip_address=None, user_agent=None, **data):
         """
         Helper method to create a guest activity log entry
         """
@@ -116,5 +116,5 @@ class ActivityLog(Base, UUIDMixin, TimestampMixin):
             description=description,
             ip_address=ip_address,
             user_agent=user_agent,
-            data=data
+            activity_data=data
         )