feat: detect done without forwarded completion

scripts/subagent_delivery_watchdog.mjs

@@ -209,6 +209,14 @@ function recomputeStatus(payload) {
     return 'not_implemented';
   }
 
+  const childRunStatus = typeof payload.childRunStatus === 'string'
+    ? payload.childRunStatus.trim().toLowerCase()
+    : null;
+
+  if (childRunStatus === 'done') {
+    return 'done_but_not_forwarded';
+  }
+
   const expectedBy = parseTime(payload.expectedBy);
   const currentTime = parseTime(payload.currentTime);