Refactor variable of front end (#13953)

### What problem does this PR solve?

api_host -> webAPI
ExternalApi -> restAPIv1

### Type of change

- [x] Refactoring


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Refactor**
* Updated internal API endpoint configuration to use consolidated base
URL constants for improved maintainability and consistency across the
application.

* **Chores**
* Updated server-side protocol validation for admin connectivity checks.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

web/src/components/document-preview/hooks.ts

@@ -1,7 +1,7 @@
 import { Authorization } from '@/constants/authorization';
 import { useGetKnowledgeSearchParams } from '@/hooks/route-hook';
 import { useGetPipelineResultSearchParams } from '@/pages/dataflow-result/hooks';
-import api, { api_host } from '@/utils/api';
+import api, { webAPI } from '@/utils/api';
 import { getAuthorization } from '@/utils/authorization-util';
 import jsPreviewExcel from '@js-preview/excel';
 import { useSize } from 'ahooks';
@@ -57,7 +57,7 @@ export const useGetDocumentUrl = (isAgent: boolean) => {
     if (isAgent) {
       return api.downloadFile + `?id=${id}&created_by=${createdBy}`;
     }
-    return `${api_host}/document/get/${documentId}`;
+    return `${webAPI}/document/get/${documentId}`;
   }, [createdBy, documentId, id, isAgent]);
 
   return url;