feat: Agent批量升级 + 版本号注入 + 服务器凭证下拉关联

- Dockerfile: ARG VERSION/BUILD_TIME 通过 ldflags 注入 agent+backend 二进制
- run.sh: 自动从 git tag 获取版本号
- docker-compose: build args 传递 VERSION/BUILD_TIME
- backend: BatchUpgradeAgent SSH下载新二进制+重启, /agent/bin 静态文件服务
- frontend: 监控大屏添加批量升级按钮 (闪电图标)
- frontend: 服务器编辑/添加表单改为凭证下拉选择器
- frontend: ServerForm 加载 /credentials 列表, 选择后自动填充用户名/认证方式

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

@@ -3,7 +3,7 @@ import React, { useState, useEffect } from 'react';
 import {
   Monitor, Plus, RefreshCw, Maximize2, Minimize2, BarChart3, Clock,
   Server, Activity, Database, Wifi, WifiOff, ArrowUpDown, ArrowUp, ArrowDown,
-  ExternalLink, Download, Trash2, Rocket
+  ExternalLink, Download, Trash2, Rocket, Zap
 } from 'lucide-react';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
@@ -104,6 +104,23 @@ const AgentTab: React.FC = () => {
     finally { setBatchUninstalling(false); }
   };
 
+  // 批量升级 Agent 到最新版本
+  const [batchUpgrading, setBatchUpgrading] = useState(false);
+  const handleBatchUpgrade = async () => {
+    const online = hosts.filter((h: any) => selIds.has(h.server_id) && h.agent_status === 'online');
+    if (online.length === 0) { toast.error('所选主机中没有在线 Agent'); return; }
+    const ids = online.map((h: any) => h.server_id);
+    const ok = await _confirm({ title: '批量升级 Agent', description: `确定升级选中的 ${ids.length} 台在线主机的 Agent 到最新版本？升级将在后台异步执行。`, confirmText: '升级', variant: 'default' });
+    if (!ok) return;
+    setBatchUpgrading(true);
+    try {
+      const res = await agentApi.batchUpgrade(ids);
+      toast.success(res?.message || `已提交：批量升级 ${ids.length} 台主机的 Agent，后台执行中，30秒后自动刷新`);
+      setTimeout(() => fetch(), 30000);
+    } catch { toast.error('提交失败'); }
+    finally { setBatchUpgrading(false); }
+  };
+
   if (loading) return <div className="text-center py-20 text-[var(--dg-text-muted)]"><Activity className="h-6 w-6 mx-auto mb-2 animate-spin" /><p className="text-xs">加载中…</p></div>;
   if (!hosts.length) return <div className="text-center py-20 text-[var(--dg-text-muted)]"><Server className="h-8 w-8 mx-auto mb-2" /><p className="text-sm">暂无服务器资产</p><p className="text-xs mt-1">请先在「服务器管理」中添加主机，然后在此安装 Agent</p></div>;
   return (
@@ -127,6 +144,9 @@ const AgentTab: React.FC = () => {
             <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="outline" className="h-7 text-xs gap-1 border-amber-500/30 text-amber-400 hover:bg-amber-500/10" onClick={handleBatchUpgrade} disabled={batchUpgrading}>
+              <Zap className="w-3 h-3" />批量升级 ({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>