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_theme.py

@@ -3,10 +3,13 @@
 Vendor theme management specific exceptions.
 """
 
-from typing import Any, Dict, Optional
+from typing import Any
 
-from .base import (BusinessLogicException, ConflictException,
-                   ResourceNotFoundException, ValidationException)
+from .base import (
+    BusinessLogicException,
+    ResourceNotFoundException,
+    ValidationException,
+)
 
 
 class VendorThemeNotFoundException(ResourceNotFoundException):
@@ -27,8 +30,8 @@ class InvalidThemeDataException(ValidationException):
     def __init__(
         self,
         message: str = "Invalid theme 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,
@@ -41,7 +44,7 @@ class InvalidThemeDataException(ValidationException):
 class ThemePresetNotFoundException(ResourceNotFoundException):
     """Raised when a theme preset is not found."""
 
-    def __init__(self, preset_name: str, available_presets: Optional[list] = None):
+    def __init__(self, preset_name: str, available_presets: list | None = None):
         details = {"preset_name": preset_name}
         if available_presets:
             details["available_presets"] = available_presets
@@ -61,8 +64,8 @@ class ThemeValidationException(ValidationException):
     def __init__(
         self,
         message: str = "Theme 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: