feat(auth): define Default/Local owner contract (#5795)

* feat(auth): define default local owner contract

* test(auth): harden default local owner matrix

---------

Co-authored-by: Alexandre Teixeira <111787685+alteixeira20@users.noreply.github.com>

src/task_scheduler.py

@@ -10,6 +10,7 @@ from datetime import datetime, timedelta, timezone
 from typing import Any, Awaitable, Callable, Dict, Tuple
 
 from core.auth import RESERVED_USERNAMES
+from src.owner_identity import REQUEST_SENTINEL_OWNERS
 from src.task_action_policy import (
     is_admin_only_task_action,
     owner_has_admin_task_privileges,
@@ -2520,7 +2521,7 @@ class TaskScheduler:
         # check-ins seeded, which then double-fire alongside the human user's
         # check-ins. This was the root cause of the duplicate 'Morning check-in'
         # rows we had to manually clean up.
-        if not owner or owner in RESERVED_USERNAMES:
+        if not owner or owner in REQUEST_SENTINEL_OWNERS:
             logger.info(f"ensure_assistant_defaults: skip synthetic owner {owner!r}")
             return
         from core.database import SessionLocal, CrewMember, ScheduledTask