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/workflows/test_integration.py

@@ -96,7 +96,7 @@ class TestIntegrationFlows:
 
         # 4. Get vendor details
         response = client.get(
-            f"/api/v1/vendor/{vendor ['vendor_code']}", headers=auth_headers
+            f"/api/v1/vendor/{vendor['vendor_code']}", headers=auth_headers
         )
         assert response.status_code == 200