Refactor system/version API to RESTful style (#13956)

### What problem does this PR solve?

Refactor version API to RESTful style. Python and go server API also
updated.
### Type of change

- [x] Refactoring



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

## Release Notes

* **Refactor**
* Migrated core API endpoints to the `/api/v1/` namespace for improved
consistency and organization.
* Standardized system version, search, and chat list endpoints under the
new API versioning structure.

* **New Features**
* Added MinIO region configuration support, allowing specification of
storage engine regional settings via environment variables or
configuration files.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

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

admin/client/ragflow_client.py

@@ -1655,7 +1655,7 @@ class RAGFlowClient:
         if self.server_type == "admin":
             response = self.http_client.request("GET", "/admin/version", use_api_base=True, auth_kind="admin")
         else:
-            response = self.http_client.request("GET", "/system/version", use_api_base=False, auth_kind="admin")
+            response = self.http_client.request("GET", "/system/version", use_api_base=True, auth_kind="admin")
 
         res_json = response.json()
         if response.status_code == 200: