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/vendor_domain.py

@@ -3,11 +3,14 @@
 Vendor domain management specific exceptions.
 """
 
-from typing import Any, Dict, Optional
 
-from .base import (BusinessLogicException, ConflictException,
-                   ExternalServiceException, ResourceNotFoundException,
-                   ValidationException)
+from .base import (
+    BusinessLogicException,
+    ConflictException,
+    ExternalServiceException,
+    ResourceNotFoundException,
+    ValidationException,
+)
 
 
 class VendorDomainNotFoundException(ResourceNotFoundException):
@@ -30,7 +33,7 @@ class VendorDomainNotFoundException(ResourceNotFoundException):
 class VendorDomainAlreadyExistsException(ConflictException):
     """Raised when trying to add a domain that already exists."""
 
-    def __init__(self, domain: str, existing_vendor_id: Optional[int] = None):
+    def __init__(self, domain: str, existing_vendor_id: int | None = None):
         details = {"domain": domain}
         if existing_vendor_id:
             details["existing_vendor_id"] = existing_vendor_id
@@ -104,7 +107,7 @@ class MultiplePrimaryDomainsException(BusinessLogicException):
 
     def __init__(self, vendor_id: int):
         super().__init__(
-            message=f"Vendor can only have one primary domain",
+            message="Vendor can only have one primary domain",
             error_code="MULTIPLE_PRIMARY_DOMAINS",
             details={"vendor_id": vendor_id},
         )