Big refactor of gift categories model

backend/app/models/gift.py

@@ -121,38 +121,47 @@ class GiftPurchase(Base, UUIDMixin):
         return f"<GiftPurchase gift_id={self.gift_id} guest_id={self.guest_id}>"
 
 
+class EventGiftCategory(Base):
+    __tablename__ = 'event_gift_categories'
+
+    event_id = Column(UUID(as_uuid=True), ForeignKey('events.id'), primary_key=True)
+    category_id = Column(UUID(as_uuid=True), ForeignKey('gift_categories.id'), primary_key=True)
+    display_order = Column(Integer, default=0)
+    is_visible = Column(Boolean, default=True)
+    created_at = Column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc), nullable=False)
+
+    # Relationships
+    event = relationship("Event", back_populates="category_associations")
+    category = relationship("GiftCategory", back_populates="event_associations")
+
+    def __repr__(self):
+        return f"<EventGiftCategory event_id={self.event_id} category_id={self.category_id}>"
+
+
 class GiftCategory(Base, UUIDMixin, TimestampMixin):
     __tablename__ = 'gift_categories'
 
     # Foreign Keys
-    event_id = Column(UUID(as_uuid=True), ForeignKey('events.id'), nullable=False)
     created_by = Column(UUID(as_uuid=True), ForeignKey('users.id'), nullable=False)
 
     # Category Details
-    name = Column(String, nullable=False)
+    name = Column(String, nullable=False, unique=True)
     description = Column(String)
 
     # Display
     icon = Column(String)  # Icon identifier or URL
     color = Column(String)  # Color code (hex/rgb)
-    display_order = Column(Integer, default=0)
-    is_visible = Column(Boolean, default=True)
 
     # Additional Settings
     custom_fields = Column(JSONB)
 
     # Relationships
-    event = relationship("Event", back_populates="gift_categories")
+    event_associations = relationship("EventGiftCategory", back_populates="category")
     gifts = relationship("GiftItem",
                          back_populates="category",
                          order_by="GiftItem.display_order")
     created_by_user = relationship("User", foreign_keys=[created_by])
 
-    # Ensure unique category names within an event
-    __table_args__ = (
-        UniqueConstraint('event_id', 'name', name='uq_event_category_name'),
-    )
-
     def __repr__(self):
         return f"<GiftCategory {self.name}>"