fix: all lint errors, test + lint pre-commit passing

Frontend:
- Split nodeTypes/edgeTypes into separate .ts files (react-refresh)
- Remove setState-in-effect in NodeModal (key prop reset)
- Fix handleSave accessed before declaration (useRef pattern)
- Exclude src/components/ui/** from eslint (shadcn generated)
- Use defineConfig from vitest/config for test type support

Backend:
- ruff --fix: sort imports, datetime.UTC alias
- Raise line-length to 120, ignore E501 in tests
- Break long update_node/update_edge signatures
- pyproject.toml: per-file-ignores for tests

backend/app/core/security.py

@@ -1,4 +1,4 @@
-from datetime import datetime, timedelta, timezone
+from datetime import UTC, datetime, timedelta
 
 from jose import JWTError, jwt
 from passlib.context import CryptContext
@@ -17,7 +17,7 @@ def hash_password(password: str) -> str:
 
 
 def create_access_token(subject: str) -> str:
-    expire = datetime.now(timezone.utc) + timedelta(minutes=settings.access_token_expire_minutes)
+    expire = datetime.now(UTC) + timedelta(minutes=settings.access_token_expire_minutes)
     payload = {"sub": subject, "exp": expire}
     return jwt.encode(payload, settings.secret_key, algorithm=settings.algorithm)