fix: agent_version 为空 & 恢复批量卸载

- 后端上报时若 agent_version 为空则不覆盖已有版本（防止旧Agent清空版本号）
- 安装/升级后写入版本号 v0.1.0（而非 installed/latest）
- DB 存量 online 主机 agent_version 补填 v0.1.0
- 前端恢复批量卸载 Agent 按钮

frontend/src/components/monitor/dashboard/GrafanaDashboard.tsx

@@ -3,7 +3,7 @@ import React, { useState, useEffect, useMemo } from 'react';
 import {
   Monitor, Plus, RefreshCw, Maximize2, Minimize2, BarChart3, Clock,
   Server, Activity, Database, Wifi, WifiOff, ArrowUpDown, ArrowUp, ArrowDown,
-  ExternalLink, Download, Rocket, PackageOpen, Loader2, Info
+  ExternalLink, Download, Rocket, PackageOpen, Loader2, Info, Trash2
 } from 'lucide-react';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
@@ -24,6 +24,7 @@ import { http } from '@/services/http';
 import { asList } from '@/components/agent/agentUtils';
 import { AgentWizard } from '@/components/agent/AgentWizard';
 import { Checkbox } from '@/components/ui/checkbox';
+import { useConfirm } from '@/components/ui/confirm-dialog';
 import { useNavigate } from 'react-router-dom';
 
 // ═══════════ Tab 配置 ═══════════
@@ -40,6 +41,7 @@ interface AgentHost { server_id: number; hostname: string; ip: string; cpu_usage
 type SortField = 'hostname' | 'agent_version' | 'agent_status' | 'cpu_usage' | 'mem_usage' | 'disk_usage' | 'region' | 'ip';
 
 const AgentTab: React.FC = () => {
+  const _confirm = useConfirm();
   const navigate = useNavigate();
   const [hosts, setHosts] = useState<AgentHost[]>([]);
   const [loading, setLoading] = useState(true);
@@ -57,6 +59,20 @@ const AgentTab: React.FC = () => {
   const [batchSubmitting, setBatchSubmitting] = useState(false);
   // 正在执行操作的主机 ID 集合（版本列 loading）
   const [operating, setOperating] = useState<Set<number>>(new Set());
+  // 批量卸载
+  const [batchUninstalling, setBatchUninstalling] = useState(false);
+  const handleBatchUninstall = async () => {
+    const ok = await _confirm({ title: '批量卸载 Agent', description: `确定卸载选中的 ${selIds.length} 台主机的 AIOps Agent？卸载将在后台异步执行。`, confirmText: '卸载', variant: 'destructive' });
+    if (!ok) return;
+    setBatchUninstalling(true);
+    try {
+      await agentApi.batchUninstall(selIds);
+      toast.success(`已提交：批量卸载 ${selIds.length} 台主机的 Agent，后台执行中，30秒后自动刷新`);
+      setSelected(new Set());
+      setTimeout(() => fetch(), 30000);
+    } catch { toast.error('提交失败'); }
+    finally { setBatchUninstalling(false); }
+  };
   const totalPages = Math.max(1, Math.ceil(hosts.length / pageSize));
   const fetch = async () => { try { setHosts(asList(await http.get('/agent/latest'))); } catch {} finally { setLoading(false); } };
   useEffect(() => { fetch(); const t = setInterval(fetch, 30000); return () => clearInterval(t); }, []);
@@ -141,9 +157,14 @@ const AgentTab: React.FC = () => {
           <Rocket className="w-3 h-3" />安装 Agent
         </Button>
         {selAny && (
-          <Button size="sm" variant="outline" className="h-7 text-xs gap-1 border-blue-500/30 text-blue-400 hover:bg-blue-500/10" onClick={openBatchDialog}>
-            <PackageOpen className="w-3 h-3" />批量部署 ({selected.size})
-          </Button>
+          <>
+            <Button size="sm" variant="outline" className="h-7 text-xs gap-1 border-blue-500/30 text-blue-400 hover:bg-blue-500/10" onClick={openBatchDialog}>
+              <PackageOpen className="w-3 h-3" />批量部署 ({selected.size})
+            </Button>
+            <Button size="sm" variant="outline" className="h-7 text-xs gap-1 border-red-500/30 text-red-400 hover:bg-red-500/10" onClick={handleBatchUninstall} disabled={batchUninstalling}>
+              <Trash2 className="w-3 h-3" />批量卸载 ({selected.size})
+            </Button>
+          </>
         )}
         <Button size="sm" variant="ghost" className="h-7 text-xs gap-1" onClick={fetch}><RefreshCw className="w-3 h-3" />刷新</Button>
       </div>