feat(portal-beheer): beheer portal + read-only catalogus viewer (closes #130) (#133)

## What & why

S-15a, the first of the S-15 (#16) split. A new **beheer** portal (medewerker realm, like behandel) shows the ZTC catalogus — the published zaaktypen — **read-only**. A beheerder logs in and sees the seeded BIG-REGISTRATIE zaaktype.

Closes #130

### The vertical

portal → BFF `GET /beheer/catalogi/zaaktypen` (medewerker realm + `beheerder` role) → ACL `GET /catalogi/zaaktypen` → ZGW Catalogi API.

- **ACL**: new read-only `GET /catalogi/zaaktypen` listing published zaaktypen (reuses the ADR-0021 Catalogi client; public-safe `identificatie`/`omschrijving`).
- **BFF**: new typed `IAclClient` + `Downstream:Acl:BaseUrl`, and `GET /beheer/catalogi/zaaktypen` behind a new `beheerder` policy (reuses the medewerker bearer scheme + realm-role lifting). OpenAPI spec + generated Angular client regenerated.
- **Keycloak**: `beheerder` realm role + `bram-beheerder` test user in the medewerker realm.
- **Frontend**: new `apps/beheer` Angular app (copied from behandel) with a read-only catalogus page; `SECURE_API_ROUTES=['/beheer/']`.
- **Infra**: `beheer` compose service (port 8143), added to `WAIT_SVCS` + CI log-dump; a Playwright e2e (beheerder login → catalogus shows BIG-REGISTRATIE).

### New boundary → ADR-0025

The BFF now reaches the **ACL directly** for the catalogus read — a new service-to-service edge (§14). The catalogus is neither a domain nor a projection concern, and §8.1 means only the ACL may read ZGW; routing through the domain would pollute it with a non-domain passthrough. §8.1/§8.3 stay intact. Recorded in **ADR-0025**.

## Definition of Done

- [x] Failing test committed before each implementation (red→green per layer: ACL, BFF, frontend).
- [x] Conventional Commits referencing #130.
- [ ] CI green — pending Gitea Actions run.
- [x] `docker compose up` brings up `beheer` (health-gated in `WAIT_SVCS`).
- [x] Docs — ADR-0025 + demo-script S-15a note.
- [x] Demo note in `docs/demo-script.md`.

## Verified locally

lint (`dotnet format`) ✓ · .NET unit (Acl 57 / Big 152 / EventSubscriber 19 / Bff 40) ✓ · frontend lint+test (8 projects) ✓ · frontend build (4 apps) ✓. Mutation ratchet: added a gateway unit test for the new `ListZaaktypenAsync` mapping so the ACL score holds. verify-stack (compose smoke + e2e) runs in CI.

## Notes for reviewers

- The BFF drops the ZGW URL from `BeheerZaaktype` (public-safe: identificatie + omschrijving only).
- The catalogus e2e asserts on the stable seeded `BIG-REGISTRATIE` (not a per-test reference), safe on the shared verify stack.
- Follow-ups: **S-15b** (#131) default-fill CRUD, **S-15c** (#132) medewerker-realm MFA.

🤖 Generated with [Claude Code](https://claude.com/claude-code)Reviewed-on: #133

infra/docker-compose.yml

@@ -380,6 +380,8 @@ services:
       Keycloak__MedewerkerAuthority: http://keycloak:8080/realms/medewerker
       Downstream__Domain__BaseUrl: http://domain:8080/
       Downstream__Projection__BaseUrl: http://projection-api:8080/
+      # The beheer catalogus read reaches the ACL directly (S-15a, ADR-0025).
+      Downstream__Acl__BaseUrl: http://acl:8080/
     ports:
       - "8080:8080"
     healthcheck:
@@ -544,6 +546,29 @@ services:
         condition: service_started
     networks: [cg]
 
+  # The beheer portal: nginx serves the Angular app and reverse-proxies /beheer to the BFF.
+  # Beheerders log in against the Keycloak medewerker realm (same realm as behandel, S-15a).
+  beheer:
+    build:
+      context: ..
+      dockerfile: apps/beheer/Dockerfile
+    image: register-referentie/beheer:dev
+    ports:
+      - "8143:80"
+    healthcheck:
+      # 127.0.0.1, not localhost: nginx listens on IPv4 only, but localhost resolves to ::1 first.
+      test: ["CMD-SHELL", "wget -q -O /dev/null http://127.0.0.1/ || exit 1"]
+      interval: 5s
+      timeout: 3s
+      retries: 5
+      start_period: 10s
+    depends_on:
+      bff:
+        condition: service_healthy
+      keycloak:
+        condition: service_started
+    networks: [cg]
+
   # ── Observability backplane (S-16a, ADR-0023) ──────────────────────────────
   # Grafana-native stack: Tempo ingests OTLP traces (the .NET services export
   # straight to it — no collector hop, S-16b), Prometheus scrapes service

infra/keycloak/realms/medewerker-realm.json

@@ -5,7 +5,8 @@
   "roles": {
     "realm": [
       { "name": "behandelaar", "description": "Behandelt registratieaanvragen" },
-      { "name": "teamlead", "description": "Teamleider behandeling" }
+      { "name": "teamlead", "description": "Teamleider behandeling" },
+      { "name": "beheerder", "description": "Beheert catalogus en default-fill (beheer-portal, S-15)" }
     ]
   },
   "clients": [
@@ -54,6 +55,16 @@
       "emailVerified": true,
       "credentials": [{ "type": "password", "value": "test123", "temporary": false }],
       "realmRoles": ["behandelaar", "teamlead"]
+    },
+    {
+      "username": "bram-beheerder",
+      "enabled": true,
+      "firstName": "Bram",
+      "lastName": "Beheerder",
+      "email": "bram@big.example.nl",
+      "emailVerified": true,
+      "credentials": [{ "type": "password", "value": "test123", "temporary": false }],
+      "realmRoles": ["beheerder"]
     }
   ]
 }