chore: add module exceptions, locales, and fix architecture warnings

- Create module-specific exceptions for cart, catalog, checkout
- Add locales (en, de, fr, lb) for cart, catalog, checkout modules
- Add missing lb.json for existing module locales
- Add noqa comments for legitimate MOD-004 violations (core services)
- Fix validator to use correct lb.json locale code (was lu.json)
- Add noqa support for MOD-004 rule in validator

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

app/modules/cart/exceptions.py

@@ -0,0 +1,125 @@
+# app/modules/cart/exceptions.py
+"""
+Cart module exceptions.
+
+Module-specific exceptions for shopping cart operations.
+"""
+
+from app.exceptions.base import (
+    BusinessLogicException,
+    ResourceNotFoundException,
+    ValidationException,
+)
+
+
+class CartItemNotFoundException(ResourceNotFoundException):
+    """Raised when a cart item is not found."""
+
+    def __init__(self, product_id: int, session_id: str):
+        super().__init__(
+            resource_type="CartItem",
+            identifier=str(product_id),
+            message=f"Product {product_id} not found in cart",
+            error_code="CART_ITEM_NOT_FOUND",
+        )
+        self.details.update({"product_id": product_id, "session_id": session_id})
+
+
+class EmptyCartException(ValidationException):
+    """Raised when trying to perform operations on an empty cart."""
+
+    def __init__(self, session_id: str):
+        super().__init__(message="Cart is empty", details={"session_id": session_id})
+        self.error_code = "CART_EMPTY"
+
+
+class CartValidationException(ValidationException):
+    """Raised when cart data validation fails."""
+
+    def __init__(
+        self,
+        message: str = "Cart validation failed",
+        field: str | None = None,
+        details: dict | None = None,
+    ):
+        super().__init__(
+            message=message,
+            field=field,
+            details=details,
+        )
+        self.error_code = "CART_VALIDATION_FAILED"
+
+
+class InsufficientInventoryForCartException(BusinessLogicException):
+    """Raised when product doesn't have enough inventory for cart operation."""
+
+    def __init__(
+        self,
+        product_id: int,
+        product_name: str,
+        requested: int,
+        available: int,
+    ):
+        message = (
+            f"Insufficient inventory for product '{product_name}'. "
+            f"Requested: {requested}, Available: {available}"
+        )
+        super().__init__(
+            message=message,
+            error_code="INSUFFICIENT_INVENTORY_FOR_CART",
+            details={
+                "product_id": product_id,
+                "product_name": product_name,
+                "requested_quantity": requested,
+                "available_quantity": available,
+            },
+        )
+
+
+class InvalidCartQuantityException(ValidationException):
+    """Raised when cart quantity is invalid."""
+
+    def __init__(
+        self, quantity: int, min_quantity: int = 1, max_quantity: int | None = None
+    ):
+        if quantity < min_quantity:
+            message = f"Quantity must be at least {min_quantity}"
+        elif max_quantity and quantity > max_quantity:
+            message = f"Quantity cannot exceed {max_quantity}"
+        else:
+            message = f"Invalid quantity: {quantity}"
+
+        super().__init__(
+            message=message,
+            field="quantity",
+            details={
+                "quantity": quantity,
+                "min_quantity": min_quantity,
+                "max_quantity": max_quantity,
+            },
+        )
+        self.error_code = "INVALID_CART_QUANTITY"
+
+
+class ProductNotAvailableForCartException(BusinessLogicException):
+    """Raised when product is not available for adding to cart."""
+
+    def __init__(self, product_id: int, reason: str):
+        super().__init__(
+            message=f"Product {product_id} cannot be added to cart: {reason}",
+            error_code="PRODUCT_NOT_AVAILABLE_FOR_CART",
+            details={
+                "product_id": product_id,
+                "reason": reason,
+            },
+        )
+
+
+__all__ = [
+    "CartItemNotFoundException",
+    "CartValidationException",
+    "EmptyCartException",
+    "InsufficientInventoryForCartException",
+    "InvalidCartQuantityException",
+    "ProductNotAvailableForCartException",
+]