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>

scripts/create_landing_page.py

@@ -12,7 +12,7 @@ from pathlib import Path
 # Add project root to path
 sys.path.insert(0, str(Path(__file__).parent.parent))
 
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 
 from sqlalchemy.orm import Session
 
@@ -65,7 +65,7 @@ def create_landing_page(
             if content:
                 existing.content = content
             existing.is_published = True
-            existing.updated_at = datetime.now(timezone.utc)
+            existing.updated_at = datetime.now(UTC)
 
             db.commit()
             print(f"✅ Updated landing page with template: {template}")
@@ -78,7 +78,7 @@ def create_landing_page(
                 content=content
                 or f"""
                     <h2>About {vendor.name}</h2>
-                    <p>{vendor.description or 'Your trusted shopping destination for quality products.'}</p>
+                    <p>{vendor.description or "Your trusted shopping destination for quality products."}</p>
 
                     <h3>Why Choose Us?</h3>
                     <ul>
@@ -95,7 +95,7 @@ def create_landing_page(
                 template=template,
                 meta_description=f"Shop at {vendor.name} for quality products and great service",
                 is_published=True,
-                published_at=datetime.now(timezone.utc),
+                published_at=datetime.now(UTC),
                 show_in_footer=False,
                 show_in_header=False,
                 display_order=0,
@@ -154,7 +154,7 @@ def list_vendors():
             if landing:
                 print(f"    Landing Page: ✅ ({landing.template})")
             else:
-                print(f"    Landing Page: ❌ None")
+                print("    Landing Page: ❌ None")
             print()
 
     finally:
@@ -220,8 +220,8 @@ if __name__ == "__main__":
     if success:
         print("\n✅ SUCCESS! Landing page is ready.")
         print("\n💡 Try different templates:")
-        print(f"   python scripts/create_landing_page.py")
-        print(f"   # Then choose: minimal, modern, or full")
+        print("   python scripts/create_landing_page.py")
+        print("   # Then choose: minimal, modern, or full")
     else:
         print("\n❌ Failed to create landing page")
         sys.exit(1)