新增: 父子任务支持(数据→后端→前端全链路,会话前基线收尾)

- df-nodes task_advance_node(父聚合推进)+ task.rs 命令(create parent_id 支持/delete 级联软删子任务)+ task_graph 工具

- 前端 Tasks 树形列表(折叠箭头/子进度徽章/缩进)+ 新建弹窗父任务下拉 + TaskDetail 父面包屑/子任务面板

- 设计文档: 父子任务支持设计-2026-08-04

src/i18n/en/taskDetail.ts

@@ -67,5 +67,13 @@ export default {
     collapse: 'Collapse',
     // Related info panel title (wide-screen right column / info grouping)
     relatedTitle: 'Related',
+    // F-260805 parent/child tasks: parent breadcrumb + subtask panel
+    parentTask: 'Parent Task',
+    childrenTitle: 'Subtasks',
+    subtaskCount: '{n} subtasks',
+    childEmpty: 'No subtasks yet',
+    addSubtask: '+ Add Subtask',
+    progressTitle: 'Progress',
+    addSubtaskFailed: 'Failed to create subtask: {msg}',
   },
 }

src/i18n/en/tasks.ts

@@ -39,6 +39,14 @@ export default {
       empty: 'No tasks yet',
     },
     confirmDelete: 'Delete task "{title}"? This action cannot be undone.',
+    // F-260805 parent/child tasks: deleting a parent cascades soft-delete of children
+    confirmDeleteWithChildren: 'Delete "{title}"? {n} subtasks will also be deleted.',
+    // F-260805 parent/child tasks: tree child progress badge / mini progress bar tooltip
+    tree: {
+      progress: 'Progress',
+    },
+    // F-260805 parent/child tasks: add-subtask entry in parent quick menu
+    addSubtask: '+ Add Subtask',
     // Quick action menu (task card quick status/priority/delete)
     quickActions: 'Quick Actions',
     quickStatus: 'Status',
@@ -64,6 +72,9 @@ export default {
       priorityHigh: 'P1 High',
       priorityMedium: 'P2 Medium',
       priorityLow: 'P3 Low',
+      // F-260805 parent/child tasks: parent dropdown in create modal
+      parentTask: 'Parent Task',
+      parentPlaceholder: 'None (top-level task)',
     },
     // Status labels (TASK_STATUS_LABELS values in constants/project.ts use these keys) — D-260616-01 aligned to backend 7 states
     status: {