add Brand Management

backend/models.py

@@ -17,12 +17,24 @@ shopping_event_products = Table(
     Column('price', Float, nullable=False)  # Price of this product at the time of this shopping event
 )
 
+class Brand(Base):
+    __tablename__ = "brands"
+    
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, nullable=False, index=True)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
+    
+    # Relationships
+    products = relationship("Product", back_populates="brand")
+
 class Product(Base):
     __tablename__ = "products"
     
     id = Column(Integer, primary_key=True, index=True)
     name = Column(String, nullable=False, index=True)
     category = Column(String, nullable=False)
+    brand_id = Column(Integer, ForeignKey("brands.id"), nullable=True)
     organic = Column(Boolean, default=False)
     weight = Column(Float, nullable=True)  # in grams or kg
     weight_unit = Column(String, default="piece")  # "g", "kg", "ml", "l", "piece"
@@ -30,6 +42,7 @@ class Product(Base):
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
     
     # Relationships
+    brand = relationship("Brand", back_populates="products")
     shopping_events = relationship("ShoppingEvent", secondary=shopping_event_products, back_populates="products")
 
 class Shop(Base):