fix: resolve all CI lint and security issues

- ruff: 602→0 errors (428 auto-fixed, pyproject.toml ignores for FastAPI patterns)
- bandit: skip B310 (urllib for vault file access is intentional)
- Fixed SIM118 (dict.keys()→dict), PERF102, SIM113, SIM117
- Created pyproject.toml with ruff + bandit config
- 285 tests still pass

backend/vault_settings.py

@@ -10,9 +10,9 @@ Current settings:
 
 import json
 import logging
-from pathlib import Path
-from typing import Dict, Any, Optional
 import threading
+from pathlib import Path
+from typing import Any
 
 logger = logging.getLogger("obsigate.vault_settings")
 
@@ -21,10 +21,10 @@ _SETTINGS_PATH = _BASE_DIR / "data" / "vault_settings.json"
 _settings_lock = threading.RLock()
 
 # In-memory cache of vault settings
-_vault_settings: Dict[str, Dict[str, Any]] = {}
+_vault_settings: dict[str, dict[str, Any]] = {}
 
 
-def load_vault_settings() -> Dict[str, Dict[str, Any]]:
+def load_vault_settings() -> dict[str, dict[str, Any]]:
     """Load vault settings from disk.
     
     Returns:
@@ -78,7 +78,7 @@ def save_vault_settings() -> None:
             raise
 
 
-def get_vault_setting(vault_name: str) -> Optional[Dict[str, Any]]:
+def get_vault_setting(vault_name: str) -> dict[str, Any] | None:
     """Get settings for a specific vault.
     
     Args:
@@ -91,7 +91,7 @@ def get_vault_setting(vault_name: str) -> Optional[Dict[str, Any]]:
         return _vault_settings.get(vault_name)
 
 
-def update_vault_setting(vault_name: str, settings: Dict[str, Any]) -> Dict[str, Any]:
+def update_vault_setting(vault_name: str, settings: dict[str, Any]) -> dict[str, Any]:
     """Update settings for a specific vault.
     
     Args:
@@ -128,7 +128,7 @@ def delete_vault_setting(vault_name: str) -> bool:
         return False
 
 
-def get_all_vault_settings() -> Dict[str, Dict[str, Any]]:
+def get_all_vault_settings() -> dict[str, dict[str, Any]]:
     """Get all vault settings.
     
     Returns: