统一客户端维护态错误弹窗

客户端维护响应统一识别并广播维护事件

AGC 与网页端根部展示维护大弹窗，收口发布、上传、资源换签和登录错误

补充维护态弹窗测试、类型检查与实施计划说明

src/components/common/MaintenanceNotice.tsx

@@ -0,0 +1,67 @@
+import { useEffect, useState } from 'react';
+
+import { MAINTENANCE_EVENT } from '../../services/apiClient';
+import { PlatformActionButton } from './PlatformActionButton';
+import { UnifiedModal } from './UnifiedModal';
+
+type MaintenanceEventDetail = {
+  code?: string;
+  status?: number;
+  requestId?: string;
+};
+
+function isMaintenanceEvent(
+  event: Event,
+): event is CustomEvent<MaintenanceEventDetail> {
+  return event.type === MAINTENANCE_EVENT;
+}
+
+/**
+ * 维护态的唯一客户端出口。请求层识别到维护响应后广播事件，页面不再各自展示业务兜底错误。
+ */
+export function MaintenanceNotice() {
+  const [open, setOpen] = useState(false);
+
+  useEffect(() => {
+    const handleMaintenance = (event: Event) => {
+      if (isMaintenanceEvent(event)) {
+        setOpen(true);
+      }
+    };
+    window.addEventListener(MAINTENANCE_EVENT, handleMaintenance);
+    return () =>
+      window.removeEventListener(MAINTENANCE_EVENT, handleMaintenance);
+  }, []);
+
+  return (
+    <UnifiedModal
+      open={open}
+      title="系统维护中"
+      description="服务正在维护，当前操作暂时无法完成。请稍后再试。"
+      onClose={() => setOpen(false)}
+      size="lg"
+      closeOnBackdrop={false}
+      showCloseButton={false}
+      portalTheme="light"
+      panelClassName="min-h-[min(42vh,28rem)]"
+      bodyClassName="flex flex-1 items-center justify-center px-6 py-10 sm:px-12 sm:py-16"
+      footerClassName="justify-center px-6 py-5 sm:px-12"
+      footer={
+        <PlatformActionButton
+          type="button"
+          onClick={() => setOpen(false)}
+          tone="primary"
+          size="md"
+          shape="pill"
+          className="min-w-36"
+        >
+          我知道了
+        </PlatformActionButton>
+      }
+    >
+      <div className="text-center text-base leading-7 text-[var(--platform-text-base)] sm:text-lg">
+        为避免维护期间出现不一致，相关页面错误会统一收口到此提示。
+      </div>
+    </UnifiedModal>
+  );
+}