feat(execution): reconcile timed-out orders safely

trex_core/domain/slot/models.py

@@ -64,6 +64,11 @@ class Slot:
     # across ticks and restarts.
     cancel_state: Optional[str] = None
     cancel_requested_at: Optional[datetime] = None
+    # Immutable dispatch clock and original KST order date. Unlike updated_at,
+    # these survive polling/cancel bookkeeping and anchor deadline/recovery.
+    order_submitted_at: Optional[datetime] = None
+    order_date: Optional[str] = None
+    cancel_attempts: int = 0
 
 
 # Canonical column contract for `Slot` (dcy-001 OQ-2 / FR-5).
@@ -95,6 +100,9 @@ EXPECTED_SLOT_FIELDS: frozenset[str] = frozenset({
     "venue",
     "cancel_state",
     "cancel_requested_at",
+    "order_submitted_at",
+    "order_date",
+    "cancel_attempts",
 })