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>

models/database/content_page.py

@@ -14,10 +14,19 @@ Features:
 - Version history support
 """
 
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 
-from sqlalchemy import (Boolean, Column, DateTime, ForeignKey, Index, Integer,
-                        String, Text, UniqueConstraint)
+from sqlalchemy import (
+    Boolean,
+    Column,
+    DateTime,
+    ForeignKey,
+    Index,
+    Integer,
+    String,
+    Text,
+    UniqueConstraint,
+)
 from sqlalchemy.orm import relationship
 
 from app.core.database import Base
@@ -77,13 +86,13 @@ class ContentPage(Base):
     # Timestamps
     created_at = Column(
         DateTime(timezone=True),
-        default=lambda: datetime.now(timezone.utc),
+        default=lambda: datetime.now(UTC),
         nullable=False,
     )
     updated_at = Column(
         DateTime(timezone=True),
-        default=lambda: datetime.now(timezone.utc),
-        onupdate=lambda: datetime.now(timezone.utc),
+        default=lambda: datetime.now(UTC),
+        onupdate=lambda: datetime.now(UTC),
         nullable=False,
     )