feat(admin): Phase 0 平台超管基础 — is_platform_admin + IsPlatformAdmin + create_platform_admin(admin/admin123) + AdminAuditLog + Admin 后台外壳与路由 gating

后端:User.is_platform_admin + migration;权限类 IsPlatformAdmin;管理命令建 admin/admin123(幂等);
AdminAuditLog 模型 + log_admin_action() helper;me/login 对无团队超管优雅返回 team=null;UserSerializer 暴露标志。
前端:routes/admin 后台外壳(分组侧栏 + 概览 + 占位)、/admin 路由解析与 gating(超管直落、非超管纠回)、
侧栏平台入口、admin-page.css(仅 token)、IconKitSvg 补图标。
测试:accounts 11/11 单测过;无头 e2e _admin-p0.mjs 全断言过 + 0 console error;tsc+build 绿。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/frontend/src/components/IconKitSvg.tsx

@@ -16,7 +16,16 @@ const iconPaths: Record<string, string> = {
   chevronRight: '<path d="m9 18 6-6-6-6"/>',
   productPlus: '<path d="M12 22V12"/><path d="M16 17h6"/><path d="M19 14v6"/><path d="M21 10.5V8a2 2 0 0 0-1-1.7l-7-4a2 2 0 0 0-2 0l-7 4A2 2 0 0 0 3 8v8a2 2 0 0 0 1 1.7l7 4a2 2 0 0 0 2 0l1.7-1"/><path d="m3.3 7 8.7 5 8.7-5"/><path d="m7.5 4.3 9 5.1"/>',
   arrowUp: '<path d="M12 19V5"/><path d="m5 12 7-7 7 7"/>',
-  helpCircle: '<circle cx="12" cy="12" r="9"/><path d="M9.5 9a2.5 2.5 0 0 1 5 0c0 1.5-2.5 2-2.5 4"/><path d="M12 17h.01"/>'
+  helpCircle: '<circle cx="12" cy="12" r="9"/><path d="M9.5 9a2.5 2.5 0 0 1 5 0c0 1.5-2.5 2-2.5 4"/><path d="M12 17h.01"/>',
+  ticket: '<path d="M2 9a3 3 0 0 1 0 6v2a2 2 0 0 0 2 2h16a2 2 0 0 0 2-2v-2a3 3 0 0 1 0-6V7a2 2 0 0 0-2-2H4a2 2 0 0 0-2 2Z"/><path d="M13 5v2"/><path d="M13 11v2"/><path d="M13 17v2"/>',
+  building: '<path d="M6 22V4a2 2 0 0 1 2-2h8a2 2 0 0 1 2 2v18Z"/><path d="M6 12H4a2 2 0 0 0-2 2v6a2 2 0 0 0 2 2h2"/><path d="M18 9h2a2 2 0 0 1 2 2v9a2 2 0 0 1-2 2h-2"/><path d="M10 6h4"/><path d="M10 10h4"/><path d="M10 14h4"/>',
+  type: '<path d="M4 7V4h16v3"/><path d="M9 20h6"/><path d="M12 4v16"/>',
+  shield: '<path d="M12 22s8-4 8-10V5l-8-3-8 3v7c0 6 8 10 8 10Z"/><path d="m9 12 2 2 4-4"/>',
+  activity: '<path d="M22 12h-4l-3 9L9 3l-3 9H2"/>',
+  server: '<rect x="2" y="3" width="20" height="8" rx="2"/><rect x="2" y="13" width="20" height="8" rx="2"/><path d="M6 7h.01"/><path d="M6 17h.01"/>',
+  gauge: '<path d="m12 14 4-4"/><path d="M3.34 19a10 10 0 1 1 17.32 0"/>',
+  sliders: '<line x1="4" x2="4" y1="21" y2="14"/><line x1="4" x2="4" y1="10" y2="3"/><line x1="12" x2="12" y1="21" y2="12"/><line x1="12" x2="12" y1="8" y2="3"/><line x1="20" x2="20" y1="21" y2="16"/><line x1="20" x2="20" y1="12" y2="3"/><line x1="2" x2="6" y1="14" y2="14"/><line x1="10" x2="14" y1="8" y2="8"/><line x1="18" x2="22" y1="16" y2="16"/>',
+  logOut: '<path d="M9 21H5a2 2 0 0 1-2-2V5a2 2 0 0 1 2-2h4"/><path d="m16 17 5-5-5-5"/><path d="M21 12H9"/>'
 };
 
 const iconAliases: Record<string, string> = {

core/frontend/src/components/app-shell.tsx

@@ -219,7 +219,7 @@ const PAGE_TO_NAV: Partial<Record<Page, Page>> = {
   settingsNotify: "settings"
 };
 
-export function Sidebar({ page, navigate, user, team, products, projects, productTotal, projectTotal, logout }: {
+export function Sidebar({ page, navigate, user, team, products, projects, productTotal, projectTotal, logout, onOpenAdmin }: {
   page: Page;
   navigate: Navigate;
   user: User;
@@ -231,6 +231,8 @@ export function Sidebar({ page, navigate, user, team, products, projects, produc
   // 退出登录。父级(App.tsx)有完整 logout 闭包时传入;未传时用自带兜底
   // (best-effort 调登出接口 + 清 token + 跳 /login),保证侧栏账户菜单的"退出"今天就可用。
   logout?: () => void;
+  // 平台超管入口:仅 user.is_platform_admin 时显示,点了进 /admin 后台
+  onOpenAdmin?: () => void;
 }) {
   const activeNav = PAGE_TO_NAV[page];
   // 徽标用后端真实总数(分页 count),不用已加载的页内条数
@@ -330,6 +332,22 @@ export function Sidebar({ page, navigate, user, team, products, projects, produc
           </a>
         ))}
       </nav>
+      {user.is_platform_admin && onOpenAdmin && (
+        <>
+          <div className="nav-section">平台</div>
+          <nav>
+            <a
+              href="/admin"
+              title="平台后台"
+              aria-label="平台后台"
+              onClick={(event) => { event.preventDefault(); setMobileNavOpen(false); onOpenAdmin(); }}
+            >
+              <IconKitSvg name="shield" />
+              <span>平台后台</span>
+            </a>
+          </nav>
+        </>
+      )}
       <div className="aside-foot">
         <div
           className="user"