feat: 错误监控面板、生成通知、社区搜索、任务队列优化

- AdminMonitor: admin用户可见的客户端错误实时监控面板，右下角浮窗
- generationNotifier: 生成完成浏览器通知 + 站内Toast
- CommunityPage: 新增搜索框，标题/描述/标签模糊匹配，防抖300ms
- App.tsx: 全局unhandled error/rejection监听上报
- WorkbenchPage: 任务并发提示改为显示当前任务数
- serverConnection: 后端client-errors路由注册
- WelcomeSplash: 欢迎按钮全程显示

Co-Authored-By: Claude Code <noreply@anthropic.com>

src/features/community/CommunityPage.tsx

@@ -7,8 +7,10 @@ import {
   PictureOutlined,
   PlusOutlined,
   RightOutlined,
+  SearchOutlined,
 } from "@ant-design/icons";
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
+import { useDebounce } from "../../hooks/useDebounce";
 import { communityClient, type ServerCommunityCase } from "../../api/communityClient";
 import WorkspacePageShell from "../../components/WorkspacePageShell";
 import OptimizedImage from "../../components/OptimizedImage";
@@ -70,6 +72,8 @@ function buildWorkflowFromServerCase(item: ServerCommunityCase, fallback: WebCan
 function CommunityPage({ projects, isAuthenticated, onStartCreate, onOpenProject, onDeleteProject, onImportWorkflow, onRequireLogin }: CommunityPageProps) {
   const [serverCases, setServerCases] = useState<ServerCommunityCase[]>([]);
   const [serverNotice, setServerNotice] = useState<string | null>(null);
+  const [query, setQuery] = useState("");
+  const debouncedQuery = useDebounce(query, 300);
   const [favoriteIds, setFavoriteIds] = useState<string[]>([]);
   const canUseProtectedAction = (action: string) => onRequireLogin?.(action) !== false;
 
@@ -260,7 +264,17 @@ function CommunityPage({ projects, isAuthenticated, onStartCreate, onOpenProject
     }
   };
 
-  const liveCases: ServerCommunityCase[] = serverCases.slice(0, 12);
+  const filteredCases = useMemo(() => {
+    const q = debouncedQuery.trim().toLowerCase();
+    if (!q) return serverCases;
+    return serverCases.filter((c) =>
+      (c.title || "").toLowerCase().includes(q) ||
+      (c.description || "").toLowerCase().includes(q) ||
+      (c.tags || []).some((t: string) => t.toLowerCase().includes(q))
+    );
+  }, [serverCases, debouncedQuery]);
+
+  const liveCases: ServerCommunityCase[] = filteredCases.slice(0, 12);
 
   return (
     <WorkspacePageShell title="社区" fullWidth className="community-page page-motion">
@@ -387,6 +401,15 @@ function CommunityPage({ projects, isAuthenticated, onStartCreate, onOpenProject
           <div>
             <h2>社区精选</h2>
           </div>
+          <label className="asset-search">
+            <SearchOutlined />
+            <input
+              value={query}
+              onChange={(e) => setQuery(e.target.value)}
+              placeholder="搜索案例..."
+            />
+            {query ? <button type="button" className="asset-search__clear" onClick={() => setQuery("")} aria-label="清除搜索">×</button> : null}
+          </label>
           {serverNotice ? <span className="studio-pill">{serverNotice}</span> : null}
         </div>
         {liveCases.length ? (
@@ -473,8 +496,8 @@ function CommunityPage({ projects, isAuthenticated, onStartCreate, onOpenProject
         ) : (
           <EmptyState
             icon={<ImportOutlined style={{ fontSize: 48 }} />}
-            title="社区暂无模板"
-            description="管理员审核通过后，画布社区案例会显示在这里。"
+            title={debouncedQuery ? "无匹配结果" : "社区暂无模板"}
+            description={debouncedQuery ? "尝试其他关键词，或清除搜索查看全部案例" : "管理员审核通过后，画布社区案例会显示在这里。"}
           />
         )}
       </section>