✨ feat(vscode): 重写注释排成一队，整个扩展一次只跑一段

OpenPencil 同一时间只能开一个画板，两段同时画会互相掐断。所有预览、所有文件的重写（第一轮和接着说）排成一队，前一段写成、出错、被叫停后按先后自动开始下一段；问 AI 照旧最多同时 3 个。
排着的那一轮记在扩展端（rewriteCurrent 的 queued），块下面写「排队中」、能取消排队，切标签页、页面重新加载后照样显示。

vscode/webview-ui/src/codeReader/BlockTree.test.tsx

@@ -1,5 +1,5 @@
 import type { BlockTreeState, RewriteTree } from './BlockTree'
-import type { ChatState } from './qa'
+import type { Ask, ChatState } from './qa'
 import type { BlockView, KindBadge } from './types'
 import { renderToStaticMarkup } from 'react-dom/server'
 import { describe, expect, it, vi } from 'vitest'
@@ -215,6 +215,18 @@ describe('「注释」一行和「重写注释」按钮', () => {
     expect(opened).toContain('aria-label="对这段注释的修改意见"')
   })
 
+  it('展开着又在写或排着队时按钮不能点；出错、停下的不挡', () => {
+    const block = view('6', 'statement', 'save()', { commentTarget: { kind: 'replace', startLine: 0, endLine: 0 } })
+    const button = (status: Ask['status']): string => {
+      const rewrite = { ...EMPTY_CHAT, available: true, open: [block.anchor], asks: [{ askId: 'r1', anchor: block.anchor, question: 'q', text: '', status }] }
+      const markup = renderToStaticMarkup(<BlockLevel blocks={[block]} tree={state(new Set(), rewrite)} />)
+      return /<button[^>]*aria-label="按注释规范重写"[^>]*>/.exec(markup)?.[0] ?? ''
+    }
+    expect(button('running')).toContain('disabled')
+    expect(button('queued')).toContain('disabled')
+    expect(button('stopped')).not.toContain('disabled')
+  })
+
   it('还没有注释的块：按钮同样在右上角那排，叫「按注释规范写注释」；不能写注释的块没有按钮', () => {
     inToolbar(html(view('3', 'statement', 'save()', { commentTarget: { kind: 'insert', line: 0 } })), '按注释规范写注释')
     expect(html(view('4', 'statement', 'save()'))).not.toContain('按注释规范')