Refactor: Remove unused API code (#13978)

### What problem does this PR solve?

Refactor: Remove unused API code

### Type of change


- [x] New Feature (non-breaking change which adds functionality)



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

## Summary by CodeRabbit

* **Style**
* Updated table header styling in dataset settings by removing a
hard-coded background color class, allowing the header to use default or
inherited component styling instead.

* **Refactor**
* Removed token management endpoints from the API service. Token
creation, listing, and removal functions are no longer available.
  * Removed the statistics data endpoint from available API routes.

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

web/src/utils/api.ts

@@ -150,11 +150,6 @@ export default {
   ask: `${restAPIv1}/chats/ask`,
   chatsMindmap: `${restAPIv1}/chats/mindmap`,
   chatsRelatedQuestions: `${restAPIv1}/chats/related_questions`,
-  // chat for external
-  createToken: `${webAPI}/api/new_token`,
-  listToken: `${webAPI}/api/token_list`,
-  removeToken: `${webAPI}/api/rm`,
-  getStats: `${webAPI}/api/stats`,
 
   // next chat
   fetchExternalChatInfo: (id: string) => `${restAPIv1}/chatbots/${id}/info`,