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/history.py

@@ -1,10 +1,10 @@
 # backend/history.py
 import json
-import time
 import logging
 import shutil
+import time
 from pathlib import Path
-from typing import List, Dict, Any, Optional
+from typing import Any
 
 logger = logging.getLogger("obsigate.history")
 
@@ -18,7 +18,7 @@ def _get_bookmarks_file(username: str) -> Path:
     HISTORY_DIR.mkdir(parents=True, exist_ok=True)
     return HISTORY_DIR / f"{username}_bookmarks.json"
 
-def _read_data(file: Path) -> List[Dict[str, Any]]:
+def _read_data(file: Path) -> list[dict[str, Any]]:
     if not file.exists():
         return []
     try:
@@ -27,7 +27,7 @@ def _read_data(file: Path) -> List[Dict[str, Any]]:
         logger.error(f"Failed to read data from {file.name}: {e}")
         return []
 
-def _write_data(file: Path, data: List[Dict[str, Any]]):
+def _write_data(file: Path, data: list[dict[str, Any]]):
     try:
         tmp = file.with_suffix(".tmp")
         tmp.write_text(json.dumps(data, indent=2, ensure_ascii=False), encoding="utf-8")
@@ -58,7 +58,7 @@ def record_open(username: str, vault: str, path: str, title: str = ""):
     
     _write_data(_get_history_file(username), history)
 
-def get_recent_opened(username: str, vault_filter: Optional[str] = None, limit: int = 20) -> List[Dict[str, Any]]:
+def get_recent_opened(username: str, vault_filter: str | None = None, limit: int = 20) -> list[dict[str, Any]]:
     """Get the most recently opened files for a user."""
     if not username:
         return []
@@ -105,7 +105,7 @@ def toggle_bookmark(username: str, vault: str, path: str, title: str = ""):
         _write_data(b_file, bookmarks)
         return True
 
-def get_bookmarks(username: str, vault_filter: Optional[str] = None) -> List[Dict[str, Any]]:
+def get_bookmarks(username: str, vault_filter: str | None = None) -> list[dict[str, Any]]:
     """Get the bookmarks for a user."""
     if not username:
         return []