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/api/v1/admin/__init__.py

@@ -24,9 +24,21 @@ IMPORTANT:
 from fastapi import APIRouter
 
 # Import all admin routers
-from . import (audit, auth, code_quality, content_pages, dashboard,
-               marketplace, monitoring, notifications, settings, users,
-               vendor_domains, vendor_themes, vendors)
+from . import (
+    audit,
+    auth,
+    code_quality,
+    content_pages,
+    dashboard,
+    marketplace,
+    monitoring,
+    notifications,
+    settings,
+    users,
+    vendor_domains,
+    vendor_themes,
+    vendors,
+)
 
 # Create admin router
 router = APIRouter()