refactor(cleanup): delete legacy storefront routes, convert cart to re-exports

Phase 6 of storefront restructure plan - delete legacy files and convert
remaining cart files to re-exports.

Deleted legacy storefront route files (now served from modules):
- app/api/v1/storefront/auth.py (→ customers module)
- app/api/v1/storefront/profile.py (→ customers module)
- app/api/v1/storefront/addresses.py (→ customers module)
- app/api/v1/storefront/carts.py (→ cart module)
- app/api/v1/storefront/products.py (→ catalog module)
- app/api/v1/storefront/orders.py (→ orders/checkout modules)
- app/api/v1/storefront/messages.py (→ messaging module)

Converted legacy cart files to re-exports:
- models/schema/cart.py → app.modules.cart.schemas
- models/database/cart.py → app.modules.cart.models
- app/services/cart_service.py → app.modules.cart.services

This reduces API-007 violations from 81 to 69 (remaining violations
are in admin/vendor routes - separate migration effort).

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

models/schema/cart.py

@@ -1,91 +1,27 @@
 # models/schema/cart.py
 """
-Pydantic schemas for shopping cart operations.
+LEGACY LOCATION - This file re-exports from the canonical module location.
+
+Canonical location: app/modules/cart/schemas/
+
+This file exists for backward compatibility. New code should import from:
+    from app.modules.cart.schemas import CartResponse, AddToCartRequest
 """
 
-from pydantic import BaseModel, ConfigDict, Field
+from app.modules.cart.schemas.cart import (
+    AddToCartRequest,
+    UpdateCartItemRequest,
+    CartItemResponse,
+    CartResponse,
+    CartOperationResponse,
+    ClearCartResponse,
+)
 
-# ============================================================================
-# Request Schemas
-# ============================================================================
-
-
-class AddToCartRequest(BaseModel):
-    """Request model for adding items to cart."""
-
-    product_id: int = Field(..., description="Product ID to add", gt=0)
-    quantity: int = Field(1, ge=1, description="Quantity to add")
-
-
-class UpdateCartItemRequest(BaseModel):
-    """Request model for updating cart item quantity."""
-
-    quantity: int = Field(..., ge=1, description="New quantity (must be >= 1)")
-
-
-# ============================================================================
-# Response Schemas
-# ============================================================================
-
-
-class CartItemResponse(BaseModel):
-    """Response model for a single cart item."""
-
-    model_config = ConfigDict(from_attributes=True)
-
-    product_id: int = Field(..., description="Product ID")
-    product_name: str = Field(..., description="Product name")
-    quantity: int = Field(..., description="Quantity in cart")
-    price: float = Field(..., description="Price per unit when added to cart")
-    line_total: float = Field(
-        ..., description="Total price for this line (price * quantity)"
-    )
-    image_url: str | None = Field(None, description="Product image URL")
-
-
-class CartResponse(BaseModel):
-    """Response model for shopping cart."""
-
-    vendor_id: int = Field(..., description="Vendor ID")
-    session_id: str = Field(..., description="Shopping session ID")
-    items: list[CartItemResponse] = Field(
-        default_factory=list, description="Cart items"
-    )
-    subtotal: float = Field(..., description="Subtotal of all items")
-    total: float = Field(..., description="Total amount (currently same as subtotal)")
-    item_count: int = Field(..., description="Total number of items in cart")
-
-    @classmethod
-    def from_service_dict(cls, cart_dict: dict) -> "CartResponse":
-        """
-        Create CartResponse from service layer dictionary.
-
-        This is a convenience method to convert the dictionary format
-        returned by cart_service into a proper Pydantic model.
-        """
-        items = [CartItemResponse(**item) for item in cart_dict.get("items", [])]
-        return cls(
-            vendor_id=cart_dict["vendor_id"],
-            session_id=cart_dict["session_id"],
-            items=items,
-            subtotal=cart_dict["subtotal"],
-            total=cart_dict["total"],
-            item_count=len(items),
-        )
-
-
-class CartOperationResponse(BaseModel):
-    """Response model for cart operations (add, update, remove)."""
-
-    message: str = Field(..., description="Operation result message")
-    product_id: int = Field(..., description="Product ID affected")
-    quantity: int | None = Field(
-        None, description="New quantity (for add/update operations)"
-    )
-
-
-class ClearCartResponse(BaseModel):
-    """Response model for clearing cart."""
-
-    message: str = Field(..., description="Operation result message")
-    items_removed: int = Field(..., description="Number of items removed from cart")
+__all__ = [
+    "AddToCartRequest",
+    "UpdateCartItemRequest",
+    "CartItemResponse",
+    "CartResponse",
+    "CartOperationResponse",
+    "ClearCartResponse",
+]