refactor(schedule): move orchestrator to application/ + review fixes (stage 8)

Follow-up to the layered refactor (review-driven):

- Move scheduling/orchestrator.py -> application/orchestrator.py
  (orchestrator is application-level coordination, not a cron-trigger
  primitive; matches the intended target tree)
- Migrate orchestrator re-exports from scheduling/__init__.py to
  application/__init__.py; scheduling/ now exposes only CronScheduler
- Rewrite imports + 5 mock.patch string targets in test_janitor.py and
  the orchestrator import in test_layering.py
- Update docstring refs in application/service.py + execution/worker.py
- Add 4 runner smoke tests (test_layering.py): _limited_log under-limit /
  empty-sentinel / above-MAX_LOG_BYTES truncation; execute_artifact
  rejects unsupported script_type with ValueError
- infrastructure/__init__.py re-exports SchedulerStorageClient so
  ``from schedule.infrastructure import SchedulerStorageClient`` is a
  stable top-level surface
- CLAUDE.md engineering note: extend the commit trail to 7476c27 and
  note the stage-8 orchestrator placement

Zero behavior change; schedule/pyproject.toml untouched. 29 tests green.

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

schedule/tests/test_janitor.py

@@ -23,7 +23,7 @@ import pytest
 
 from common.db.models import ScheduleNodeRuns
 from common.eventing import utcnow
-from schedule.scheduling.orchestrator import NODE_FINISHED_EVENT, DispatchOrchestrator
+from schedule.application.orchestrator import NODE_FINISHED_EVENT, DispatchOrchestrator
 
 
 def _make_orchestrator() -> DispatchOrchestrator:
@@ -195,7 +195,7 @@ async def test_reap_kills_running_row_past_deadline() -> None:
     fake_session.add = MagicMock()
 
     with patch(
-        "schedule.scheduling.orchestrator.session_scope",
+        "schedule.application.orchestrator.session_scope",
         return_value=_open_session_scope(fake_session),
     ):
         killed = await orch._reap_stuck_node_runs()
@@ -223,7 +223,7 @@ async def test_reap_skips_healthy_row() -> None:
     fake_session.add = MagicMock()
 
     with patch(
-        "schedule.scheduling.orchestrator.session_scope",
+        "schedule.application.orchestrator.session_scope",
         return_value=_open_session_scope(fake_session),
     ):
         killed = await orch._reap_stuck_node_runs()
@@ -266,7 +266,7 @@ async def test_reap_processes_multiple_rows_in_one_pass() -> None:
     fake_session.add = MagicMock()
 
     with patch(
-        "schedule.scheduling.orchestrator.session_scope",
+        "schedule.application.orchestrator.session_scope",
         return_value=_open_session_scope(fake_session),
     ):
         killed = await orch._reap_stuck_node_runs()
@@ -289,7 +289,7 @@ async def test_janitor_loop_propagates_cancellation() -> None:
         raise asyncio.CancelledError
 
     with patch(
-        "schedule.scheduling.orchestrator.asyncio.sleep",
+        "schedule.application.orchestrator.asyncio.sleep",
         side_effect=cancel_on_sleep,
     ):
         with pytest.raises(asyncio.CancelledError):
@@ -321,7 +321,7 @@ async def test_janitor_loop_continues_after_reap_exception() -> None:
             raise asyncio.CancelledError
 
     with patch(
-        "schedule.scheduling.orchestrator.asyncio.sleep",
+        "schedule.application.orchestrator.asyncio.sleep",
         side_effect=_count_sleeps,
     ):
         with pytest.raises(asyncio.CancelledError):