feat: auto-reconcile stale holding mirrors

Closes #94

tests/application/test_snapshot_scheduler.py

@@ -60,11 +60,15 @@ def test_run_once_uses_authoritative_core_holdings_broker(monkeypatch):
     projected_broker = object()
     authoritative_broker = object()
     unmanaged_store = object()
+    auto_store = SimpleNamespace(apply_holding_mirror=lambda _command: False)
     captured = {}
 
     def _capture(**kwargs):
         captured["broker"] = kwargs["broker"]
         captured["unmanaged_position_store"] = kwargs.get("unmanaged_position_store")
+        captured["portfolio_items"] = kwargs.get("portfolio_items")
+        captured["cost_basis_port"] = kwargs.get("cost_basis_port")
+        captured["auto_reconcile_store"] = kwargs.get("auto_reconcile_store")
         return {}
 
     monkeypatch.setattr(
@@ -79,12 +83,17 @@ def test_run_once_uses_authoritative_core_holdings_broker(monkeypatch):
         slot_repo=object(),
         slot_service=SimpleNamespace(instance_key="inst-1"),
         unmanaged_position_store=unmanaged_store,
+        cost_basis_port=read,
+        auto_reconcile_store=auto_store,  # type: ignore[arg-type]
     )
     sched._reconcile_slots = lambda _items: None
 
     assert sched.run_once() is True
     assert captured["broker"] is authoritative_broker
     assert captured["unmanaged_position_store"] is unmanaged_store
+    assert captured["portfolio_items"] == read.items
+    assert captured["cost_basis_port"] is read
+    assert captured["auto_reconcile_store"] is auto_store
 
 
 def test_swap_preserves_warning_for_carried_over_portfolio():