refactor(services): one periodic-task shape, one APScheduler job shape, one token hash, one summary rule — the services pass of the shape audit (#2830, milestone 296)

- background.start_periodic(interval, work, label=) replaces the three hand-rolled
  while-True/sleep/try loops in logging, auth and notifications.
- services/scheduler.ScheduledJob replaces the four private BackgroundScheduler
  copies in recurrence/version_pinning/trash/db_maintenance schedulers; public
  start_/stop_/reschedule_ surfaces unchanged.
- api_keys.hash_token is the one sha256 helper; auth.py used to inline it 5x.
- auth.is_registration_open reads via settings.get_admin_setting; notification
  prefs read via settings.get_setting; _fire_share_email uses _get_user_email.
- projects.get_project_summary / milestones.get_project_milestone_summary are
  now the one-id view of their batch siblings instead of a second copy of the
  queries; sharing.best_permission_by (was _deduplicate_by_permission) is the
  one rank-dedup, now also used by list_projects_for_user.
- backup: the row builders for every section both exporters carry are named
  functions, so a column added to one export cannot silently miss the other.
- iso() from models.base replaces the attr.isoformat()-if-attr-else-None idiom
  and db_maintenance._iso across services; backup keeps its explicit shape.
- trash.py hoists the sql_delete/timedelta imports it re-imported per function.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_api_keys.py

@@ -5,7 +5,7 @@ from unittest.mock import AsyncMock, MagicMock, patch
 import pytest
 
 from scribe.services.api_keys import (
-    _hash_key,
+    hash_token,
     _key_prefix,
     generate_key,
     create_api_key,
@@ -29,7 +29,7 @@ def test_generate_key_uniqueness():
 
 def test_hash_key_is_sha256():
     key = "fmcp_testkey"
-    h = _hash_key(key)
+    h = hash_token(key)
     expected = hashlib.sha256(key.encode()).hexdigest()
     assert h == expected
 
@@ -79,7 +79,7 @@ async def test_lookup_key_returns_none_for_unknown():
 
 def test_hash_key_deterministic():
     key = "fmcp_some_test_key_value"
-    assert _hash_key(key) == _hash_key(key)
+    assert hash_token(key) == hash_token(key)
 
 
 @pytest.mark.asyncio