fix(tasks): add explicit parentTaskId field to addTask shape — makes !t.parentTaskId filter intent clear

src/lib/stores/page.svelte.js

@@ -231,6 +231,7 @@ export function addTask(task) {
     doneAt: null,
     createdAt: new Date().toISOString(),
     sourceTranscriptId: task.sourceTranscriptId || null,
+    parentTaskId: task.parentTaskId || null,
     notes: "",
   };
   tasks.unshift(newTask);