fix: WorkflowEditor 下拉过滤禁用用户 — getEligibleUsers 增加 is_active 条件

- 审核阶段: 只显示 is_active=true 且角色为 admin/dba/auditor 的用户
- 执行阶段: 只显示 is_active=true 且角色为 admin/dba 的用户
- 禁用用户不再出现在审批流程编辑器下拉列表中

frontend/src/pages/WorkflowPage.tsx

@@ -281,9 +281,10 @@ function WorkflowEditorModal({ workflow, users, onClose, onSaved }: EditorProps)
   };
 
   const getEligibleUsers = (stepType: string) => {
-    if (stepType === 'audit') return users.filter(u => ['admin', 'superadmin', 'dba', 'auditor'].includes(u.role));
-    if (stepType === 'execute') return users.filter(u => ['admin', 'superadmin', 'dba'].includes(u.role));
-    return users;
+    const active = users.filter(u => u.is_active);
+    if (stepType === 'audit') return active.filter(u => ['admin', 'superadmin', 'dba', 'auditor'].includes(u.role));
+    if (stepType === 'execute') return active.filter(u => ['admin', 'superadmin', 'dba'].includes(u.role));
+    return active;
   };
 
   const toggleAllUsers = (idx: number) => {