feat: 修复仪表盘数据管线 — 补充应用发布种子数据 + 修复limit参数解析 + LDAP认证集成 + User类型完善

后端改进:
- 修复 dashboard/recent-alerts 的 limit 参数解析 (原代码错误地将数字解析为日期)
- 为 dashboard/recent-releases 添加 limit 参数解析支持
- 新增 generateAppReleases 种子数据生成函数 (10条应用发布记录)
- 修复 AlertEvent 的 rule_name/rule_id/severity 数据一致性
- 添加 go-ldap/ldap/v3 依赖并集成 LDAP 认证处理器
- 添加 seed.go 自动种子数据初始化 (admin用户+LDAP配置)
- User model 添加 AuthSource/LDAPConfig 字段

前端改进:
- 修复 User 类型定义以匹配后端 API (real_name/is_admin/auth_source等)
- 修复 Header.tsx 的 real_name 属性引用导致 TypeScript 编译错误
- 统一 API 服务层、暗色主题样式、组件联调优化

验证:
- go build ./... 编译通过
- npm run build 构建通过
- 仪表盘发布历史、告警消息等区域数据正常展示
- 健康检查 /health 正常

frontend/src/components/layout/Header.tsx

@@ -1,7 +1,7 @@
 import { useState } from 'react';
 import { NavLink } from 'react-router-dom';
 import { cn } from '@/lib/utils';
-import { useThemeStore, useTabStore, useNotificationStore } from '@/store';
+import { useThemeStore, useTabStore, useNotificationStore, useUserStore } from '@/store';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { Badge } from '@/components/ui/badge';
@@ -31,15 +31,27 @@ import {
   Rocket,
   Server,
   Cloud,
+  Palette,
+  Check,
 } from 'lucide-react';
 import { formatDistanceToNow } from '@/lib/utils';
+import { useTheme, THEME_OPTIONS } from '@/hooks/useTheme';
 
 export function Header() {
   const { sidebarCollapsed, toggleSidebar } = useThemeStore();
   const { tabs, activeTab, removeTab, setActiveTab } = useTabStore();
   const { notifications, unreadCount, markAsRead, markAllAsRead } = useNotificationStore();
+  const { user, logout } = useUserStore();
+  const { theme, setTheme } = useTheme();
   const [searchValue, setSearchValue] = useState('');
 
+  const handleLogout = () => {
+    logout();
+    window.location.href = '/login';
+  };
+
+  const displayName = user?.real_name || user?.username || '管理员';
+
   const getNotificationIcon = (type: string) => {
     switch (type) {
       case 'error':
@@ -101,6 +113,39 @@ export function Header() {
 
         {/* Right: Actions */}
         <div className="flex items-center gap-2">
+          {/* Theme Switcher */}
+          <DropdownMenu>
+            <DropdownMenuTrigger asChild>
+              <Button variant="ghost" size="icon" className="h-8 w-8 text-slate-400 hover:text-slate-100">
+                <Palette className="h-4 w-4" />
+              </Button>
+            </DropdownMenuTrigger>
+            <DropdownMenuContent align="end" className="w-56 bg-slate-800 border-slate-700">
+              <DropdownMenuLabel className="text-slate-300">主题切换</DropdownMenuLabel>
+              <DropdownMenuSeparator className="bg-slate-700" />
+              {THEME_OPTIONS.map((option) => (
+                <DropdownMenuItem
+                  key={option.id}
+                  className={cn(
+                    'flex items-center gap-2 cursor-pointer focus:bg-slate-700 focus:text-slate-100',
+                    theme === option.id ? 'text-slate-100' : 'text-slate-300'
+                  )}
+                  onClick={() => setTheme(option.id)}
+                >
+                  <span
+                    className="w-3 h-3 rounded-full shrink-0 ring-2 ring-slate-900"
+                    style={{ backgroundColor: option.primaryColor }}
+                  />
+                  <div className="flex-1 min-w-0">
+                    <span className="text-sm font-medium">{option.name}</span>
+                    <span className="block text-xs text-slate-500 truncate">{option.description}</span>
+                  </div>
+                  {theme === option.id && <Check className="h-4 w-4 text-blue-400 shrink-0" />}
+                </DropdownMenuItem>
+              ))}
+            </DropdownMenuContent>
+          </DropdownMenu>
+
           {/* Create New */}
           <DropdownMenu>
             <DropdownMenuTrigger asChild>
@@ -201,9 +246,9 @@ export function Header() {
             <DropdownMenuTrigger asChild>
               <Button variant="ghost" className="h-8 gap-2 px-2 text-slate-300 hover:text-slate-100">
                 <div className="w-6 h-6 rounded-full bg-blue-600 flex items-center justify-center text-white text-xs font-medium">
-                  管
+                  {displayName.charAt(0)}
                 </div>
-                <span className="hidden md:inline text-sm">管理员</span>
+                <span className="hidden md:inline text-sm">{displayName}</span>
               </Button>
             </DropdownMenuTrigger>
             <DropdownMenuContent align="end" className="w-48 bg-slate-800 border-slate-700">
@@ -218,7 +263,7 @@ export function Header() {
                 账号设置
               </DropdownMenuItem>
               <DropdownMenuSeparator className="bg-slate-700" />
-              <DropdownMenuItem className="text-red-400 focus:bg-slate-700 focus:text-red-400">
+              <DropdownMenuItem className="text-red-400 focus:bg-slate-700 focus:text-red-400" onClick={handleLogout}>
                 <LogOut className="h-4 w-4 mr-2" />
                 退出登录
               </DropdownMenuItem>