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>

tests/integration/api/v1/test_inventory_endpoints.py

@@ -8,7 +8,6 @@ from models.database.inventory import Inventory
 @pytest.mark.api
 @pytest.mark.inventory
 class TestInventoryAPI:
-
     def test_set_inventory_new_success(self, client, auth_headers):
         """Test setting inventory for new GTIN successfully"""
         inventory_data = {
@@ -445,7 +444,7 @@ class TestInventoryAPI:
         """Test invalid inventory operations return InvalidInventoryOperationException"""
         # This would test business logic validation
         # The exact scenario depends on your business rules
-        pass  # Implementation depends on specific business rules
+        # Implementation depends on specific business rules
 
     def test_get_inventory_without_auth_returns_invalid_token(self, client):
         """Test that inventory endpoints require authentication returns InvalidTokenException"""