feat: 知识库标签/实体关联跳转 + 会话重连容错

前端:
- Wiki 标签与实体改为可点击，弹出 RelatedNotesDialog 查看关联知识
- 知识库首次进入自动打开最近笔记，避免空白阅读区
- 流式重连识别 "Run not found"，清理 sessionStorage 残留 key 并静默回退历史

后端:
- 线程鉴权区分 not found / not accessible，并支持 DB 切换产生的孤儿线程认领
- run 查询/join 在内存未命中时回退持久化存储，重启后返回干净的终止 SSE 而非 404

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

@@ -152,7 +152,10 @@ function getStreamErrorMessage(error: unknown): string {
  */
 function isThreadNotAccessibleError(message: string): boolean {
   const lowered = message.toLowerCase();
-  if (/thread\s+[\w-]{8,}\s+not\s+found/i.test(message)) {
+  // Backend now returns "not found" (no row + no checkpoint) and
+  // "not accessible" (row owned by another user / stale login session) as
+  // distinct details — both mean the current user can't use this thread.
+  if (/thread\s+[\w-]{8,}\s+not\s+(found|accessible)/i.test(message)) {
     return true;
   }
   // Fallback: a bare 404/403 from the threads endpoint when the SDK has
@@ -163,6 +166,21 @@ function isThreadNotAccessibleError(message: string): boolean {
   );
 }
 
+/**
+ * Detect a "Run <id> not found" 404 from the LangGraph SDK.
+ *
+ * The SDK persists the in-flight run id under ``lg:stream:{threadId}`` in
+ * sessionStorage and, on mount, auto-``joinStream``s it to resume a dropped
+ * SSE. After a backend restart the in-memory run registry is gone, so the join
+ * 404s — and the SDK only clears that key on reconnect *success*, never on
+ * failure. So every switch back into the conversation re-fires the same 404.
+ * We detect it here to clear the stale key ourselves and stay silent (the
+ * conversation renders from history; there is nothing live to reconnect to).
+ */
+function isRunNotFoundError(message: string): boolean {
+  return /run\s+[\w-]{8,}\s+not\s+found/i.test(message);
+}
+
 function buildCurrentUserLabel(): string {
   const auth = getStoredAuth();
   if (!auth) {
@@ -335,6 +353,19 @@ export function useThreadStream({
     onError(error) {
       setOptimisticMessages([]);
       const message = getStreamErrorMessage(error);
+      // A stale auto-reconnect ("Run <id> not found") after a backend restart:
+      // drop the dirty ``lg:stream:{threadId}`` key so switching back into this
+      // conversation stops re-firing the same 404, and render from history
+      // silently — there is no live run to rejoin.
+      if (isRunNotFoundError(message)) {
+        const staleThreadId = threadIdRef.current ?? onStreamThreadId ?? null;
+        if (staleThreadId && runMetadataStorageRef.current) {
+          runMetadataStorageRef.current.removeItem(
+            `lg:stream:${staleThreadId}`,
+          );
+        }
+        return;
+      }
       // A "thread not found" 404 almost always means the URL points at a
       // thread from a previous login session — either this tab outlived a
       // logout/re-login or the thread genuinely belongs to a different user.