修复多会话任务栏抖动、会话跳回与停止失效 (#264)

* fix(web): stabilize active task ordering

* fix(chat): preserve navigation during conversation startup

* fix(tasks): guarantee hard cancellation

* fix(chat): bind navigation and hard stop targets

* fix(chat): prevent replay from reclaiming navigation

web/static/js/router.js

@@ -18,6 +18,12 @@ function buildHashForPage(pageId) {
 
 let chatConversationFromHashSeq = 0;
 
+function cancelScheduledChatConversationFromHash() {
+    chatConversationFromHashSeq++;
+    setChatConversationRestorePending('', false);
+}
+window.cancelScheduledChatConversationFromHash = cancelScheduledChatConversationFromHash;
+
 function setChatConversationRestorePending(conversationId, pending) {
     const container = document.querySelector('.chat-container');
     if (!container) return;
@@ -123,6 +129,9 @@ function switchPage(pageId) {
     if (!targetPage) return;
     if (pageId !== 'chat') {
         setChatConversationRestorePending('', false);
+        if (currentPage === 'chat' && typeof window.abandonChatConversationForPageNavigation === 'function') {
+            window.abandonChatConversationForPageNavigation();
+        }
     }
 
     // 导航点击会修改 hash，随后浏览器还会触发 hashchange。