feat: Go后端LDAP真实对接 — AES-256-GCM密码加解密 + 登录LDAP fallback

- 新增 crypto.go: AES-256-GCM 加解密，与 Python backend 兼容
- auth.go: Login 添加 LDAP fallback（本地优先→LDAP绑定→自动创建本地用户）
- ldap.go: 实现真实 LDAP 连接/用户搜索/密码验证/OU列表/用户列表
- 所有 LDAP 操作解密 admin_password 后使用
- 新增/更新密码存储时加密
- router.go: 补充 delete-user 路由
- 添加 go-ldap/v3 依赖

frontend/src/components/EditInstanceDialog.tsx

@@ -121,7 +121,7 @@ export default function EditInstanceDialog({ instance, open, onClose, onSaved, m
       if (mode === 'clone') {
         payload.db_type = instance.db_type;
         if (!password) {
-          alert('克隆数据源需要重新输入密码');
+          setError('克隆数据源需要重新输入密码');
           setSubmitting(false);
           return;
         }

frontend/src/pages/WorkflowPage.tsx

@@ -475,7 +475,8 @@ export default function WorkflowPage() {
       setLoading(true);
       setError(null);
       const data = await workflowApi.list();
-      setItems(Array.isArray(data) ? data : []);
+      const normalized = (Array.isArray(data) ? data : []).map((w: any) => ({ ...w, steps: w.steps || [] }));
+      setItems(normalized);
     } catch (err: unknown) {
       const msg = (err as { response?: { data?: { detail?: string } } })?.response?.data?.detail || '获取审批流程失败';
       setError(msg);
@@ -588,7 +589,7 @@ export default function WorkflowPage() {
               { label: '流程总数', value: items.length, icon: GitBranch, color: 'text-blue-400', bg: 'bg-blue-400/10' },
               { label: '已启用', value: items.filter((w) => w.is_active).length, icon: CheckCircle, color: 'text-green-400', bg: 'bg-green-400/10' },
               { label: '默认流程', value: items.filter((w) => w.is_default).length, icon: Star, color: 'text-yellow-400', bg: 'bg-yellow-400/10' },
-              { label: '总步骤数', value: items.reduce((acc, w) => acc + w.steps.length, 0), icon: Users, color: 'text-purple-400', bg: 'bg-purple-400/10' },
+              { label: '总步骤数', value: items.reduce((acc, w) => acc + (w.steps?.length || 0), 0), icon: Users, color: 'text-purple-400', bg: 'bg-purple-400/10' },
             ].map((s, i) => (
               <Card key={i} className="dg-card">
                 <CardContent className="p-4 flex items-center gap-3">