task-7(壳层/路由): 根路由跳转到首个可见页面，移除硬编码默认页

helpers.firstVisiblePath 深度优先返回首个可路由页面，无页面返回空串；
store 增加 firstVisible；守卫在根路由/无权限时跳首个可见页，全部无页面则
停留根路由展示无菜单空态，删除 redirect:'/account/users' 硬编码。

admin-frontend-vue/tests/task-7.test.ts

@@ -0,0 +1,77 @@
+import test from 'node:test'
+import assert from 'node:assert/strict'
+import { readSource } from './helpers.ts'
+import { firstVisiblePath } from '../src/router/helpers.ts'
+import type { AdminMenuNode } from '../src/types/admin.ts'
+
+function node(partial: Partial<AdminMenuNode> & { key: string; name: string }): AdminMenuNode {
+  return { key: partial.key, name: partial.name, route: partial.route, children: partial.children }
+}
+
+const NESTED: AdminMenuNode[] = [
+  node({ key: 'a', name: '组A', children: [node({ key: 'a1', name: '无路由' })] }),
+  node({ key: 'b', name: '组B', children: [
+    node({ key: 'b1', name: '用户', route: '/account/users' }),
+    node({ key: 'b2', name: '菜单', route: '/account/menus' }),
+  ] }),
+]
+
+test('test_task_007_first_route_redirect_normal_primary_path', () => {
+  // 正常主路径：深度优先返回第一个可见页面。
+  assert.equal(firstVisiblePath(NESTED), '/account/users')
+})
+
+test('test_task_007_first_route_redirect_normal_variant_input', () => {
+  // 正常变体：另一棵树返回其自身首个可见页，不依赖固定页。
+  const tree: AdminMenuNode[] = [
+    node({ key: 'x', name: '顶级', route: '/shop/list' }),
+    node({ key: 'y', name: '后置', route: '/tasks/list' }),
+  ]
+  assert.equal(firstVisiblePath(tree), '/shop/list')
+})
+
+test('test_task_007_first_route_redirect_normal_repeated_operation_is_idempotent', () => {
+  // 正常重复：结果稳定、不修改输入。
+  const snapshot = JSON.stringify(NESTED)
+  assert.equal(firstVisiblePath(NESTED), firstVisiblePath(NESTED))
+  assert.equal(JSON.stringify(NESTED), snapshot)
+})
+
+test('test_task_007_first_route_redirect_boundary_empty_input', () => {
+  // 边界空值：无任何菜单返回空串，不硬编码缺省页。
+  assert.equal(firstVisiblePath([]), '')
+  assert.equal(firstVisiblePath(undefined), '')
+  assert.equal(firstVisiblePath(null), '')
+})
+
+test('test_task_007_first_route_redirect_boundary_single_item', () => {
+  // 边界单元素：仅一个顶层页面时返回它。
+  assert.equal(firstVisiblePath([node({ key: 's', name: '单页', route: '/solo' })]), '/solo')
+})
+
+test('test_task_007_first_route_redirect_boundary_limit_or_missing_field', () => {
+  // 边界上限：只有无路由子项的分组不产出可见页。
+  const onlyEmptyGroups: AdminMenuNode[] = [
+    node({ key: 'g', name: '空组', children: [node({ key: 'c', name: '不可点' })] }),
+  ]
+  assert.equal(firstVisiblePath(onlyEmptyGroups), '')
+})
+
+test('test_task_007_first_route_redirect_invalid_input_rejected', () => {
+  // 异常输入：畸形节点被跳过并继续找下一个可见页。
+  const withMalformed: AdminMenuNode[] = [
+    { key: 'bad', name: '畸形', route: '' } as unknown as AdminMenuNode,
+    node({ key: 'ok', name: '可见', route: '/fine' }),
+  ]
+  assert.equal(firstVisiblePath(withMalformed), '/fine')
+})
+
+test('test_task_007_first_route_redirect_dependency_failure_returns_actionable_message', () => {
+  // 依赖失败：根跳转由会话首个可见页驱动，不再硬编码 account/users。
+  const router = readSource('src/router/index.ts')
+  assert.equal(router.includes('redirect: \'/account/users\''), false, '禁止硬编码根跳转缺省页')
+  assert.equal(router.includes('firstVisible'), true, '守卫必须使用会话首个可见页')
+  const store = readSource('src/stores/admin-session.ts')
+  assert.match(store, /firstVisible:/)
+  assert.match(store, /firstVisiblePath/)
+})