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_pagination.py

@@ -10,7 +10,6 @@ from models.database.vendor import Vendor
 @pytest.mark.database
 @pytest.mark.products
 class TestPagination:
-
     def test_product_pagination_success(self, client, auth_headers, db):
         """Test pagination for product listing successfully"""
         import uuid
@@ -224,7 +223,6 @@ class TestPagination:
         unique_suffix = str(uuid.uuid4())[:8]
 
         # Create multiple vendors for pagination testing
-        from models.database.vendor import Vendor
 
         vendors = []
         for i in range(15):