feat: Add GitHub Actions CI for PR protection

- Add CI workflow with Python (ruff lint, security tests) and UI (ESLint, TypeScript, build) jobs
- Add ruff, mypy, pytest to requirements.txt
- Add pyproject.toml with ruff configuration
- Fix import sorting across Python files (ruff --fix)
- Fix test_security.py expectations to match actual security policy
- Remove invalid 'eof' command from ALLOWED_COMMANDS

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

api/database.py

@@ -10,7 +10,7 @@ from typing import Optional
 
 from sqlalchemy import Boolean, Column, Integer, String, Text, create_engine
 from sqlalchemy.ext.declarative import declarative_base
-from sqlalchemy.orm import sessionmaker, Session
+from sqlalchemy.orm import Session, sessionmaker
 from sqlalchemy.types import JSON
 
 Base = declarative_base()

api/migration.py

@@ -11,7 +11,7 @@ from datetime import datetime
 from pathlib import Path
 from typing import Optional
 
-from sqlalchemy.orm import sessionmaker, Session
+from sqlalchemy.orm import Session, sessionmaker
 
 from api.database import Feature