Summary

Fixes #37019

When SWAGGER_UI_ENABLED=true, the API serves Swagger UI doc pages (e.g. /api/swagger-ui.html, /console/api/swagger-ui.html). Flask-RESTX serves the UI's static assets (CSS/JS) from the app-level /swaggerui path.

The bundled Docker nginx config (docker/nginx/conf.d/default.conf.template) proxies the doc-page routes (/api, /console/api, /openapi, …) to the api service, but has no route for /swaggerui. As a result the doc page loads, but every static asset request 404s through nginx and the page renders blank.

This PR adds a /swaggerui location that proxies to the api service, matching the other API routes. This is exactly the workaround the issue reporter verified.

location /swaggerui {
  proxy_pass http://api:5001;
  include proxy.conf;
}

The block contains no ${...} placeholders, so it is unaffected by the entrypoint's envsubst step. The route is only meaningful when SWAGGER_UI_ENABLED is on; when disabled the API simply doesn't register those assets, so adding the proxy is harmless.

Screenshots

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change. (N/A — nginx config has no test harness.)
• I've updated the documentation accordingly.
• I ran make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods (N/A — change is limited to a Docker nginx config template).