技能展示适配持久化 + 参考文献收集与新对话流式修复

- 后端新增 skill_display_adapters 表，持久化每个技能的 display 配置与 sample
  payload；/api/skills 列表、详情、设置接口同步读写
- 新增 /api/skills/{name}/display-sample 端点，编辑器优先加载库中样例
- 前端展示适配面板改为从后端加载持久样例，无样例时提示"自动识别"
- 参考文献收集修复：仅在 bash/shell/python 等执行类工具上从参数推断技能
  名，避免 read_file / web_fetch 误匹配；引用列表纳入最新一条助手消息
- ChatBox 改用「最新 human → 最新 ai」窗口收集引用，并仅保留 citation
  模式
- 修复「新对话」点击后已发消息消失：useThreadStream 只在 threadId 切回
  空值时重置/中止 SSE，避免 onCreated 分配 id 时把刚开始的流打断；
  ChatPage 在 landing 状态隐藏 MessageList，移除 KeyedChatPage remount
- 技能详情对话框：所有者可查看源码与文件 tab（不再要求管理员）
- LocalSandbox：Windows PowerShell 5 路径下把 && 重写为 ;，并以
  UTF-8 解码 subprocess 输出，避免中文乱码
- knowledge-search-v2 mock 样例改为中文固定测试数据

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend-web/src/core/threads/hooks.ts

@@ -315,13 +315,23 @@ export function useThreadStream({
   const threadStreamRef = useRef(thread);
   threadStreamRef.current = thread;
 
-  // Reset thread-local pending UI state when switching between threads so
-  // optimistic messages and in-flight guards do not leak across chat views.
-  // Also abort any in-flight SSE from the previous thread: without this,
-  // clicking "新对话" mid-stream leaves the old run firing onUpdate events
-  // against the now-detached thread context, which manifests as the page
-  // appearing unresponsive to the navigation.
+  // Reset thread-local pending UI state when the caller actually switches AWAY
+  // from a thread (threadId becomes nullish). This is the "click 新对话 / open
+  // a fresh chat" signal — abort the in-flight SSE and clear optimistic state.
+  //
+  // We deliberately do NOT reset on every threadId change. During a normal
+  // "user just sent the first message on /chats/new" flow, useThreadStream
+  // sees threadId transition from undefined (the landing state) to the
+  // server-assigned thread id once onCreated fires. Stopping the stream and
+  // clearing optimistic messages in that case is exactly what made submitted
+  // questions visually disappear — the live run that just started would be
+  // aborted by the very effect intended to reset stale state.
   useEffect(() => {
+    if (threadId != null) {
+      // Forward direction: starting or continuing with a real thread.
+      // No reset needed; the upstream useStream will load history for this id.
+      return;
+    }
     const prevThread = threadStreamRef.current;
     if (prevThread?.isLoading) {
       try {