✨ feat(vscode): 问 AI 收起再展开、重启后接着这块最近的会话问；代码改了对不上的问答不再显示

vscode/src/codeReader/qa/qaMap.ts

@@ -88,3 +88,8 @@ export function withoutEntry(map: QaMap, key: string, anchor: string, entryId: s
   delete next[key]
   return threads.length > 0 ? { ...next, [key]: threads } : next
 }
+
+/** 再问 anchor 那块时接着的会话：这块最近一次问答的会话 id；没问过、或那次没记会话 id 时没有，重新开会话。 */
+export function latestSession(threads: readonly QaThread[] | undefined, anchor: string): string | undefined {
+  return threads?.find(thread => thread.anchor === anchor)?.entries.at(-1)?.sessionId || undefined
+}