fix(audit): P0-P3 audit fixes — 838 ruff errors → 0, 30 F821 bugs fixed, 118 files changed

- P0: hooks.py 3-tuple fix, trigger_dispatcher Contract, contacts/plugin unregister_actions_by_owner
- P0: 5 test files — check_permission mocks removed, hardcoded DB credential → env var
- P1: attachment_service DmsFile via Contract helper, restore_registry/history_hooks dedup
- P1: mail/plugin restore unregister, mcp_client datetime.now(UTC), saved_views/filters patterns
- P1: ProtectedRoute fail-closed, 13 test assertion fixes (bcrypt, DB-URLs, SECRET_KEYs)
- P2: deprecated notifications → post_system_message (3 files), forgejo Base, report_generator lazy import
- P2: webhooks permissions, deps.py/roles.py plugin perms removed, import_export default
- P2: address/tags/entity_links patterns removed, worker.py Contract-Umgehungen fixed
- P2: 28 frontend TODOs (hardcoded constants, deprecated notification API)
- P3: dead code, duplicates, deprecated imports, private attr, __import__ inline
- P3: 8 frontend TODOs (LucideIcons, inline styles, XSS, i18n)
- ruff: 838 → 0 (612 auto-fix + 246 manual + 27 F821 regression fix)
- F821: 30 → 0 (AutomationDefinition, DmsFile, user_id, Path, Any, String)
- Contract-Umgehungen: 2 neue gefunden (worker.py:169, worker.py:280) und gefixt

app/core/resilience.py

@@ -137,7 +137,7 @@ def _is_transient_db_error(exc: Exception) -> bool:
     if isinstance(exc, _DB_RETRYABLE_EXC):
         return True
     try:
-        from sqlalchemy.exc import OperationalError, DBAPIError
+        from sqlalchemy.exc import DBAPIError, OperationalError
         if isinstance(exc, OperationalError):
             return True
         if isinstance(exc, DBAPIError):
@@ -162,7 +162,6 @@ async def retry_db(
     base_delay: float = 0.1,
     **kwargs: Any,
 ) -> T:
-    last_exc: Exception | None = None
     for attempt in range(max_retries):
         try:
             result = await func(*args, **kwargs)
@@ -170,7 +169,6 @@ async def retry_db(
                 logger.info("DB operation succeeded on retry %d", attempt + 1)
             return result
         except Exception as exc:
-            last_exc = exc
             if not _is_transient_db_error(exc):
                 raise
             if attempt < max_retries - 1: