feat(parser): support PaddleOCR-VL API key

[langcaiye]

Summary

• add an optional paddleocr_vl_api_key setting for the self-hosted PaddleOCR-VL parser
• send Authorization: Bearer <API Key> on self-hosted PaddleOCR-VL availability checks and /layout-parsing parse requests
• expose the optional API Key field in Parser Engine settings and update API typings / i18n / swagger schema

Closes #1721

Test plan

go test ./internal/infrastructure/docparser

npm run type-check was also run. It fails with pre-existing unrelated TypeScript errors that are reproducible on upstream main (3b317f7e) in files such as src/api/agent/index.ts, src/api/embed/index.ts, and src/views/knowledge/KnowledgeBase.vue.

[lyingbug]

This field is not part of the official PaddleOCR/PaddleX self-hosted /layout-parsing API. The official PaddleX serving docs only define the request body (file, fileType, etc.) and do not document any auth header.
Do you have some related docs about it ?

[langcaiye]

This field is not part of the official PaddleOCR/PaddleX self-hosted /layout-parsing API. The official PaddleX serving docs only define the request body (file, fileType, etc.) and do not document any auth header. Do you have some related docs about it ?

Thanks for pointing this out. You are right: this is not part of the official PaddleX self-hosted /layout-parsing API, and the previous field name/description made that unclear.

I updated the PR to rename the setting to paddleocr_vl_bearer_token and clarified that it is only for deployments where the self-hosted service is protected by an external auth gateway or reverse proxy. Official PaddleX Serving does not require this field, and leaving it empty keeps the official API behavior unchanged.

I also kept backward-compatible reading of the old paddleocr_vl_api_key field internally, but it is no longer exposed in the public config schema.