* fix(web): resolve upstream URLs at runtime
* fix(web): keep unconfigured upstreams same-origin
* fix(web): restore dev-only localhost fallbacks for API and docs upstreams
`next dev` on a developer machine now falls back to the conventional
http://localhost:8080 backend (honoring BACKEND_PORT) and
http://localhost:4000 docs origin when nothing is configured, so a bare
`pnpm dev:web` keeps proxying out of the box. Builds and the runtime
proxy keep the strict resolvers, so prebuilt images still leave unset
upstreams unproxied.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---------
Co-authored-by: Naiyuan Qing <145280634+NevilleQingNY@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>