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/unit/services/test_product_service.py

@@ -1,15 +1,17 @@
 # tests/test_product_service.py
 import pytest
 
-from app.exceptions import (InvalidMarketplaceProductDataException,
-                            MarketplaceProductAlreadyExistsException,
-                            MarketplaceProductNotFoundException,
-                            MarketplaceProductValidationException,
-                            ValidationException)
+from app.exceptions import (
+    InvalidMarketplaceProductDataException,
+    MarketplaceProductAlreadyExistsException,
+    MarketplaceProductNotFoundException,
+    MarketplaceProductValidationException,
+)
 from app.services.marketplace_product_service import MarketplaceProductService
-from models.database.marketplace_product import MarketplaceProduct
-from models.schema.marketplace_product import (MarketplaceProductCreate,
-                                               MarketplaceProductUpdate)
+from models.schema.marketplace_product import (
+    MarketplaceProductCreate,
+    MarketplaceProductUpdate,
+)
 
 
 @pytest.mark.unit