feat(behandelportal): WP-63 aanvraag status lifecycle enum

Model the full ADR-0002 lifecycle (Ingediend/InBehandeling/
MeerInfoGevraagd/Goedgekeurd/Afgewezen) as a backend enum backing the
existing AanvraagStatusDto.Tag string, and widen the FE union/parse
boundary/switches to match. Ingediend/MeerInfoGevraagd aren't reachable
yet (no behandelaar transition exists) — that's WP-65. Zero DTO shape
change, so gen:api has no drift.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/src/BigRegister.Api/Contracts/Mappers.cs

@@ -40,15 +40,18 @@ public static class Mappers
   // Goedgekeurd once past the processing window, else In behandeling; a manual case
   // stays In behandeling forever (awaits the unbuilt backoffice). Pure — testable
   // by passing different `now` values without waiting for the wall clock.
+  //
+  // Ingediend/MeerInfoGevraagd (AanvraagStatusTag, WP-63) aren't produced here yet — no
+  // behandelaar action exists to reach them (WP-65 adds the transition endpoint).
   public static AanvraagStatusDto ToStatusDto(this Aanvraag a, DateTimeOffset now)
   {
     if (!a.Submitted)
       return new("Concept", StepIndex: a.StepIndex, StepCount: a.StepCount);
     if (a.Reden is not null)
-      return new("Afgewezen", Referentie: a.Referentie, Reden: a.Reden);
+      return new(AanvraagStatusTag.Afgewezen.ToString(), Referentie: a.Referentie, Reden: a.Reden);
     if (a.AutoApprovable && now > a.SubmittedAt!.Value + ApplicationStore.ProcessingWindow)
-      return new("Goedgekeurd", Referentie: a.Referentie);
-    return new("InBehandeling", Referentie: a.Referentie, Manual: !a.AutoApprovable);
+      return new(AanvraagStatusTag.Goedgekeurd.ToString(), Referentie: a.Referentie);
+    return new(AanvraagStatusTag.InBehandeling.ToString(), Referentie: a.Referentie, Manual: !a.AutoApprovable);
   }
 
   public static ApplicationSummaryDto ToSummaryDto(this Aanvraag a, DateTimeOffset now) => new(

backend/src/BigRegister.Api/Data/ApplicationStore.cs

@@ -3,6 +3,16 @@ using BigRegister.Domain.Submissions;
 
 namespace BigRegister.Api.Data;
 
+/// <summary>
+/// The post-submission aanvraag status lifecycle (ADR-0002, WP-63): Ingediend → In
+/// behandeling → (Meer info gevraagd ⇄) → Goedgekeurd/Afgewezen. Concept (pre-submission,
+/// the wizard draft) isn't part of this enum — see <see cref="Aanvraag.Submitted"/>.
+/// <see cref="Ingediend"/> and <see cref="MeerInfoGevraagd"/> are not reachable yet: no
+/// endpoint sets them (that's WP-65's behandelaar-facing mutation) — modelled here so the
+/// contract is ready when it does.
+/// </summary>
+public enum AanvraagStatusTag { Ingediend, InBehandeling, MeerInfoGevraagd, Goedgekeurd, Afgewezen }
+
 /// <summary>
 /// An application (aanvraag) — the system of record the dashboard reads. A wizard
 /// creates one as a Concept on its first step, syncs its draft snapshot per step,

backend/tests/BigRegister.Tests/ApplicationTests.cs

@@ -205,4 +205,15 @@ public class ApplicationTests(TestWebApplicationFactory factory) : IClassFixture
     Assert.Equal("InBehandeling", status.Tag);
     Assert.True(status.Manual);
   }
+
+  // WP-63: the published lifecycle (ADR-0002) must name exactly these five tags, in this
+  // order — ToStatusDto's string literals must keep matching Enum.ToString(), and Ingediend/
+  // MeerInfoGevraagd (unreachable until WP-65 adds the behandelaar transition) stay defined.
+  [Fact]
+  public void AanvraagStatusTag_covers_the_published_lifecycle()
+  {
+    Assert.Equal(
+        new[] { "Ingediend", "InBehandeling", "MeerInfoGevraagd", "Goedgekeurd", "Afgewezen" },
+        Enum.GetNames<AanvraagStatusTag>());
+  }
 }