## What & why
Closes#96. The portal nginx configs hardcode `resolver 127.0.0.11` (Docker's embedded DNS) for their variable `proxy_pass` to the BFF, so on rootless **podman** (network-specific aardvark DNS) every proxied call 502'd — the portals loaded and login worked, but no in-app data flowed.
Add a shared `/docker-entrypoint.d` hook (`apps/portal-nginx-resolver.sh`, wired into all three portal Dockerfiles) that rewrites the resolver from the container's own `/etc/resolv.conf` at startup: a **no-op on Docker** (nameserver *is* 127.0.0.11) and **correct on podman** (rewrites to e.g. 10.89.0.1). nginx.conf is unchanged (the hardcoded value is the substitution anchor).
## How verified
Built the behandel image and ran it on the compose network under podman: the hook rewrote the config to `resolver 10.89.0.1`, and `GET /behandel/werkbak` proxied to the BFF returning **401** (auth), not 502. On Docker the nameserver is 127.0.0.11 so the substitution is a no-op and CI/e2e behaviour is unchanged.
Reviewed-on: #97
The app loads /config.json at startup (main.ts) so the OIDC authority is set per
environment from one build; appConfig becomes a factory and derives redirectUrl +
secureApiOrigin from the app origin (same-origin as the BFF). A multi-stage
Dockerfile builds the app and serves it via nginx, reverse-proxying /self-service
+ /openbaar to the bff (relative URLs → no CORS); nginx resolves the BFF at request
time. The compose image bakes config.json with the keycloak:8080 authority so the
browser's token issuer matches the BFF (ADR-0010).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
