refactor: modernize code quality tooling with Ruff

- Replace black, isort, and flake8 with Ruff (all-in-one linter and formatter)
- Add comprehensive pyproject.toml configuration
- Simplify Makefile code quality targets
- Configure exclusions for venv/.venv in pyproject.toml
- Auto-fix 1,359 linting issues across codebase

Benefits:
- Much faster builds (Ruff is written in Rust)
- Single tool replaces multiple tools
- More comprehensive rule set (UP, B, C4, SIM, PIE, RET, Q)
- All configuration centralized in pyproject.toml
- Better import sorting and formatting consistency

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/exceptions/product.py

@@ -3,16 +3,19 @@
 Product (vendor catalog) specific exceptions.
 """
 
-from typing import Optional
 
-from .base import (BusinessLogicException, ConflictException,
-                   ResourceNotFoundException, ValidationException)
+from .base import (
+    BusinessLogicException,
+    ConflictException,
+    ResourceNotFoundException,
+    ValidationException,
+)
 
 
 class ProductNotFoundException(ResourceNotFoundException):
     """Raised when a product is not found in vendor catalog."""
 
-    def __init__(self, product_id: int, vendor_id: Optional[int] = None):
+    def __init__(self, product_id: int, vendor_id: int | None = None):
         details = {"product_id": product_id}
         if vendor_id:
             details["vendor_id"] = vendor_id
@@ -79,8 +82,8 @@ class InvalidProductDataException(ValidationException):
     def __init__(
         self,
         message: str = "Invalid product data",
-        field: Optional[str] = None,
-        details: Optional[dict] = None,
+        field: str | None = None,
+        details: dict | None = None,
     ):
         super().__init__(
             message=message,
@@ -96,8 +99,8 @@ class ProductValidationException(ValidationException):
     def __init__(
         self,
         message: str = "Product validation failed",
-        field: Optional[str] = None,
-        validation_errors: Optional[dict] = None,
+        field: str | None = None,
+        validation_errors: dict | None = None,
     ):
         details = {}
         if validation_errors: