重构+优化: CR-04+06 AiChat 流式渲染改进 + CR-10 useRendered DRY 抽

- CR-04: splitBlocks 正则切块改 marked.lexer() tokens 遍历(type=code 的 .raw 整块,其余按双换行切),正确处理行首空格/4+反引号嵌套/未闭合围栏——lexer 与 parse 同 marked 实例同 gfm 规则,切块边界与渲染边界一致。
- CR-06: watch(mdReady) 翻 true 时主动 scheduleStreamParse 重算,修首屏 marked 慢+暂无 delta 致末段停留 escapeFallback 纯文本。
- CR-10: useMarkdown 抽 useRendered(computed 读 mdReady+renderMd + ensureLoaded 幂等预热),4 view(TaskDetail/ProjectDetail/Ideas/Knowledge)删手写 renderedDesc computed + onMounted loadMarkdown 重复,loadMarkdown 提模块级。DRY 行为零变化。
批4 wlnazlvdc,vue-tsc 0 err

src/views/TaskDetail.vue

@@ -99,7 +99,7 @@ import { ref, computed, onMounted, watch } from 'vue'
 import { useRoute } from 'vue-router'
 import { taskApi, projectApi } from '../api'
 import { formatDate } from '../utils/time'
-import { useMarkdown } from '../composables/useMarkdown'
+import { useRendered } from '../composables/useMarkdown'
 import {
   taskStatusLabel,
   taskStatusClass,
@@ -108,16 +108,6 @@ import {
 } from '../constants/project'
 import type { TaskRecord, ProjectRecord } from '../api/types'
 
-// B-24:任务描述 Markdown 渲染(复用 AiChat 同款渲染器,模块级单例)
-const { renderMd, loadMarkdown, mdReady } = useMarkdown()
-
-// 描述渲染依赖 mdReady 响应式:loadMarkdown 完成前 escapeFallback 纯文本,完成后 mdReady 翻转
-// 触发 computed 重算(B-24 漏响应式致 v-html=renderMd 首次纯文本后不重算,代码块不渲染)
-const renderedDescription = computed(() => {
-  void mdReady.value
-  return renderMd(task.value?.description ?? '')
-})
-
 const route = useRoute()
 
 const loading = ref(true)
@@ -127,6 +117,12 @@ const projects = ref<ProjectRecord[]>([])
 
 const taskId = computed(() => route.params.id as string)
 
+// B-24:任务描述 Markdown 渲染(复用 AiChat 同款渲染器,模块级单例),useRendered 封装
+// computed(读 mdReady 触发响应式 + renderMd)+ ensureLoaded(幂等预热)
+const { rendered: renderedDescription, ensureLoaded } = useRendered(
+  () => task.value?.description ?? '',
+)
+
 const projectName = computed(() => {
   const p = projects.value.find(p => p.id === task.value?.project_id)
   return p?.name ?? task.value?.project_id ?? '—'
@@ -159,7 +155,7 @@ function refresh() {
 watch(taskId, () => { load() })
 
 onMounted(() => {
-  loadMarkdown() // 后台预热 Markdown 渲染器(模块单例,与 AiChat 共享),不阻塞 load
+  ensureLoaded() // 后台预热 Markdown 渲染器(模块单例,与 AiChat 共享),不阻塞 load
   load()
 })
 </script>