feat(admin): art-design-pro integration with local session auth

P1b Task 9: apps/admin based on art-design-pro v3.0.2 (tag, commit
d224dd4; source recorded in apps/admin/SOURCE.md), trimmed to
layout/login/i18n/request/table-form core. Login wired to real
POST /v1/auth/password (single-token session), Bearer header on all
requests, 401 interceptor logout+redirect, request-driven sliding
renewal (refresh at ~80% TTL, single-flight), best-effort
POST /v1/auth/logout on user-menu logout. One protected stub page
(相册管理). Dev port 5176 strictPort + /v1 proxy to 8080. Admin keeps
its own eslint9 flat config; root eslint ignores apps/admin/**.
vitest unit tests for renewal pacing + Playwright e2e (guard redirect,
localized wrong-password error, login lands on stub, token persists
across reload, logout clears session).

Co-Authored-By: Claude Code <noreply@anthropic.com>

apps/admin/src/views/exception/404/index.vue

@@ -0,0 +1,16 @@
+<!-- 404页面 -->
+<template>
+  <ArtException
+    :data="{
+      title: '404',
+      desc: $t('exceptionPage.404'),
+      btnText: $t('exceptionPage.gohome'),
+      imgUrl
+    }"
+  />
+</template>
+
+<script setup lang="ts">
+  import imgUrl from '@imgs/svg/404.svg'
+  defineOptions({ name: 'Exception404' })
+</script>