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.py

@@ -3,11 +3,15 @@
 Vendor management specific exceptions.
 """
 
-from typing import Any, Dict, Optional
+from typing import Any
 
-from .base import (AuthorizationException, BusinessLogicException,
-                   ConflictException, ResourceNotFoundException,
-                   ValidationException)
+from .base import (
+    AuthorizationException,
+    BusinessLogicException,
+    ConflictException,
+    ResourceNotFoundException,
+    ValidationException,
+)
 
 
 class VendorNotFoundException(ResourceNotFoundException):
@@ -63,7 +67,7 @@ class VendorNotVerifiedException(BusinessLogicException):
 class UnauthorizedVendorAccessException(AuthorizationException):
     """Raised when user tries to access vendor they don't own."""
 
-    def __init__(self, vendor_code: str, user_id: Optional[int] = None):
+    def __init__(self, vendor_code: str, user_id: int | None = None):
         details = {"vendor_code": vendor_code}
         if user_id:
             details["user_id"] = user_id
@@ -81,8 +85,8 @@ class InvalidVendorDataException(ValidationException):
     def __init__(
         self,
         message: str = "Invalid vendor data",
-        field: Optional[str] = None,
-        details: Optional[Dict[str, Any]] = None,
+        field: str | None = None,
+        details: dict[str, Any] | None = None,
     ):
         super().__init__(
             message=message,
@@ -98,8 +102,8 @@ class VendorValidationException(ValidationException):
     def __init__(
         self,
         message: str = "Vendor validation failed",
-        field: Optional[str] = None,
-        validation_errors: Optional[Dict[str, str]] = None,
+        field: str | None = None,
+        validation_errors: dict[str, str] | None = None,
     ):
         details = {}
         if validation_errors:
@@ -134,7 +138,7 @@ class IncompleteVendorDataException(ValidationException):
 class MaxVendorsReachedException(BusinessLogicException):
     """Raised when user tries to create more vendors than allowed."""
 
-    def __init__(self, max_vendors: int, user_id: Optional[int] = None):
+    def __init__(self, max_vendors: int, user_id: int | None = None):
         details = {"max_vendors": max_vendors}
         if user_id:
             details["user_id"] = user_id