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/.gitignore

@@ -0,0 +1,12 @@
+node_modules
+.DS_Store
+dist
+dist-ssr
+*.local
+.cursorrules
+
+# Auto-generated files（unplugin 产物已提交入库：turbo typecheck 可独立运行，
+# 不必先跑一次 vite dev/build 生成声明；.auto-import.json 仅 eslint 全局用，不入库）
+.auto-import.json
+test-results/
+playwright-report/