feat(infra): single-file toggle between apps-profile dev modes

Reduce the apps-profile mode switch (localhost / VSCode tunnel vs
HTTPS hostname) to a single file: infra/local/.env. Today the
toggle requires editing both apps/portal-bff/.env (the four
ENTRA_*_REDIRECT_URI) and infra/local/.env (NX_SERVE_CONFIGURATION).
After this PR, apps/portal-bff/.env stays at its localhost defaults
regardless — native nx serve outside Docker keeps working untouched
— and infra/local/.env carries the entire mode-specific block.

- dev.compose.yml portal-bff service: the four ENTRA_*_REDIRECT_URI
  are added to the environment: block with
  ${VAR:-localhost-default} interpolation. Compose's environment:
  wins over env_file:, so the BFF inside the container sees the
  override when set and the localhost default otherwise.
- infra/local/.env.example: the trailing Apps block is restructured
  as two clearly-labelled profiles (Mode A — Localhost / DEFAULT;
  Mode B — HTTPS hostname, commented template).
- apps/portal-bff/.env.example: comment block above the redirect URI
  defaults now explains that they stay at localhost regardless and
  points at the compose-level override in infra/local/.env.
- infra/README.md: new "Switching between dev modes — localhost vs
  hostname" subsection between "Dockerised app dev mode" and
  "HTTPS dev-server setup" with a comparison table and per-mode
  step-by-step.

infra/local/dev.compose.yml

@@ -240,6 +240,21 @@ services:
       DATABASE_URL: 'postgresql://${POSTGRES_USER:-portal}:${POSTGRES_PASSWORD}@postgres:5432/${POSTGRES_DB:-portal_dev}?schema=public'
       REDIS_URL: 'redis://default:${REDIS_PASSWORD}@redis:6379/0'
       OTEL_EXPORTER_OTLP_ENDPOINT: 'http://otel-collector:4318/v1/traces'
+      # OIDC redirect URIs. Driven by infra/local/.env so switching
+      # between the two access modes — `localhost` (default; VSCode
+      # Remote-SSH port-forwarding) and `https` hostname (the
+      # ADR-0030 mkcert path) — is a single-file change. Unset →
+      # localhost defaults; set in infra/local/.env to override with
+      # an `https://apf-portal.dev-XX.local:…` hostname. See the
+      # "Switching between dev modes" subsection of infra/README.md.
+      # Compose `environment` overrides `env_file`, so the BFF's
+      # own .env stays at localhost (so native `nx serve` works
+      # untouched) and only `infra/local/.env` carries the
+      # docker-apps-mode override.
+      ENTRA_REDIRECT_URI: ${ENTRA_REDIRECT_URI:-http://localhost:3000/api/auth/callback}
+      ENTRA_POST_LOGOUT_REDIRECT_URI: ${ENTRA_POST_LOGOUT_REDIRECT_URI:-http://localhost:4200/}
+      ENTRA_ADMIN_REDIRECT_URI: ${ENTRA_ADMIN_REDIRECT_URI:-http://localhost:3000/api/admin/auth/callback}
+      ENTRA_ADMIN_POST_LOGOUT_REDIRECT_URI: ${ENTRA_ADMIN_POST_LOGOUT_REDIRECT_URI:-http://localhost:4300/}
     # Secrets (Entra / session / jwks) come from the BFF's own dev env.
     # `required: false` so SPA-only devs can `up` without it — the BFF
     # then fails its own boot-time config validators with a clear message