fix(KB-601): fix atomicWriteTaskJson missing directory error

- Fix atomicWriteTaskJson to ensure parent directory exists before writing
- Add changeset for unpause missing directory fix
- Remove deprecated backup commands and related code
- Clean up unused settings fields and API routes
- Remove task comments and merge details components
- Update store tests to reflect directory fix behavior

packages/core/src/store.ts

@@ -398,6 +398,7 @@ export class TaskStore extends EventEmitter<TaskStoreEvents> {
     const taskJsonPath = join(dir, "task.json");
     const tmpPath = join(dir, "task.json.tmp");
     this.suppressWatcher(taskJsonPath);
+    await mkdir(dir, { recursive: true }); // Ensure directory exists
     await writeFile(tmpPath, JSON.stringify(task, null, 2));
     await rename(tmpPath, taskJsonPath);
   }