feat(acl): GET /catalogi/zaaktypen lists published zaaktypen (refs #130)

services/acl/Acl.Api/Program.cs

@@ -85,6 +85,12 @@ app.MapPost("/documenten", async (StoreDocumentRequest body, AclService acl, Can
     return Results.Ok(new { informatieobjectUrl = url.ToString() });
 });
 
+// List the published zaaktypen — the read-only catalogus the beheer portal shows (S-15a). The BFF
+// proxies this behind medewerker-realm + beheerder authorization; the ACL trusts its callers (§8.3)
+// and is the only code allowed to read the ZGW Catalogi API (§8.1).
+app.MapGet("/catalogi/zaaktypen", async (AclService acl, CancellationToken ct) =>
+    Results.Ok(await acl.ListZaaktypenAsync(ct)));
+
 app.Run();
 
 public sealed record OpenZaakRequest(string Bsn, string Reference);

services/acl/Acl.Application/AclService.cs

@@ -45,8 +45,7 @@ public sealed class AclService(IZaakGateway gateway, AclDefaults defaults, IZaak
     /// <summary>The published zaaktypen, for the beheer catalogus viewer (S-15a). Read-only passthrough:
     /// no default-fill, the ACL is simply the only code allowed to read ZGW (§8.1).</summary>
     public Task<IReadOnlyList<ZaaktypeSummary>> ListZaaktypenAsync(CancellationToken ct = default) =>
-        // ponytail: stub for the red test; real passthrough lands in the green commit.
-        Task.FromResult<IReadOnlyList<ZaaktypeSummary>>([]);
+        gateway.ListZaaktypenAsync(ct);
 
     /// <summary>The zaak's reference (its ZGW identificatie), for the read projection (#78).</summary>
     public Task<string> GetZaakReferenceAsync(Uri zaakUrl, CancellationToken ct = default)

services/acl/Acl.Infrastructure/OpenZaakGateway.cs

@@ -170,9 +170,15 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
         return new Uri(match.Url);
     }
 
-    public Task<IReadOnlyList<ZaaktypeSummary>> ListZaaktypenAsync(CancellationToken ct = default) =>
-        // ponytail: stub for the red test; real Catalogi read lands in the green commit.
-        throw new NotImplementedException();
+    public async Task<IReadOnlyList<ZaaktypeSummary>> ListZaaktypenAsync(CancellationToken ct = default)
+    {
+        // Only published zaaktypen (status=definitief excludes concepts) — the read-only catalogus the
+        // beheer portal shows. Public-safe fields only.
+        var page = await GetAsync<ZaaktypePage>("/catalogi/api/v1/zaaktypen?status=definitief", "zaaktypen", ct);
+        return (page.Results ?? [])
+            .Select(z => new ZaaktypeSummary(z.Identificatie ?? "", z.Omschrijving ?? "", new Uri(z.Url)))
+            .ToList();
+    }
 
     // GETs an absolute-by-path ZGW resource with auth (no CRS — catalogi is not a geo API).
     private async Task<T> GetAsync<T>(string pathAndQuery, string label, CancellationToken ct)
@@ -350,7 +356,8 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
 
     private sealed record ZaaktypeDto(
         [property: JsonPropertyName("url")] string Url,
-        [property: JsonPropertyName("identificatie")] string? Identificatie);
+        [property: JsonPropertyName("identificatie")] string? Identificatie,
+        [property: JsonPropertyName("omschrijving")] string? Omschrijving = null);
 
     private sealed record InformatieobjecttypePage(
         [property: JsonPropertyName("results")] IReadOnlyList<InformatieobjecttypeDto>? Results);