### Summary
The FunASR provider added in #17171 defaults to a local
`http://localhost:8000/v1` server, but it still inherited the global
API-key requirement and unconditionally built an Authorization header.
This prevented the default unauthenticated self-hosted deployment from
working. The transcription path also dereferenced a missing model name
while building its multipart request.
This change:
- allows an empty API key for FunASR, matching other local providers
- omits the Authorization header when no key is configured while
preserving trimmed Bearer authentication when one is provided
- validates and trims the ASR model name before building the multipart
request, returning an error instead of panicking
- adds HTTP-level regression coverage for unauthenticated
transcription/model listing and optional authentication
### Summary
As title
verif ied from CLI
```
RAGFlow(api/default)> asr with 'paraformer@test@funasr' audio './internal/test.wav' param '{"language": "en"}'
+----------------------------------------------------------------------------------------------------------------------+
| text |
+----------------------------------------------------------------------------------------------------------------------+
| The examination and testimony of the experts enabled the commission to conclude that five shots may have been fired. |
+----------------------------------------------------------------------------------------------------------------------+
```
---
<img width="2876" height="1377" alt="image"
src="https://github.com/user-attachments/assets/4cee62c6-1c71-43ce-b398-4d9fbff33c3c"
/>
```bash
INFO: 127.0.0.1:51910 - "POST /v1/audio/transcriptions HTTP/1.1" 200 OK██████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████| 1/1 [00:00<00:00, 2.19it/s]
INFO: 127.0.0.1:60934 - "GET /v1/models HTTP/1.1" 200 OK%|███████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████| 1/1 [00:00<00:00, 2.10it/s]
```
---------
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
