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_default_content_pages.py

@@ -26,7 +26,7 @@ Usage:
 """
 
 import sys
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 from pathlib import Path
 
 # Add project root to path
@@ -496,12 +496,12 @@ def create_default_pages(db: Session) -> None:
             meta_description=page_data["meta_description"],
             meta_keywords=page_data["meta_keywords"],
             is_published=True,
-            published_at=datetime.now(timezone.utc),
+            published_at=datetime.now(UTC),
             show_in_footer=page_data["show_in_footer"],
             show_in_header=page_data.get("show_in_header", False),
             display_order=page_data["display_order"],
-            created_at=datetime.now(timezone.utc),
-            updated_at=datetime.now(timezone.utc),
+            created_at=datetime.now(UTC),
+            updated_at=datetime.now(UTC),
         )
 
         db.add(page)
@@ -511,7 +511,7 @@ def create_default_pages(db: Session) -> None:
     db.commit()
 
     print("\n" + "=" * 70)
-    print(f"Summary:")
+    print("Summary:")
     print(f"  Created: {created_count} pages")
     print(f"  Skipped: {skipped_count} pages (already exist)")
     print(f"  Total:   {created_count + skipped_count} pages")