refactor: rename Application → Aanvraag across the wire (Step 1/8)

The wire said Application, the domain said Aanvraag — one aggregate with
two names at every hop. Rename the backend DTOs and the /applications
route to /aanvragen, regenerate the typed client, and rename the frontend
adapter/store to match.

Renamed: ApplicationSummaryDto/DetailDto, CreateApplicationRequest,
SubmitApplicationRequest/Response → Aanvraag* equivalents;
ApplicationsAdapter/Store → AanvragenAdapter/Store;
applications.adapter.ts/applications.store.ts → aanvragen.*.

Left untouched: the admin Case/Zaak vocabulary (/admin/cases,
AdminCasesStore) — a separate read model, not part of this rename; the
internal BigRegister.Domain.Applications namespace and the Applications
EF table (renaming those needs a new EF migration, out of scope here).

Part of the dashboard-readability refactor (see the approved plan).

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

backend/tests/BigRegister.Tests/Acceptance/IntakeSubmissionTests.cs

@@ -9,7 +9,7 @@ namespace BigRegister.Tests.Acceptance;
 
 /// <summary>
 /// Behaviour-level tests for the scholing-threshold enforcement (WP-69) over
-/// <c>POST /applications/{id}/submit</c> (the wizard's real path — WP-72 deleted the legacy
+/// <c>POST /aanvragen/{id}/submit</c> (the wizard's real path — WP-72 deleted the legacy
 /// <c>POST /intakes</c> endpoint this once also covered). Built through the <see
 /// cref="Given"/> type-state builder, mirroring <see cref="BesluitLifecycleTests"/> rather
 /// than the full wizard/upload dance — the builder's default owner IS <see
@@ -28,7 +28,7 @@ public class IntakeSubmissionTests(TestWebApplicationFactory factory) : IClassFi
   }
 
   private Task<HttpResponseMessage> Submit(string id, object body) =>
-      _client.PostAsJsonAsync($"/api/v1/applications/{id}/submit", body);
+      _client.PostAsJsonAsync($"/api/v1/aanvragen/{id}/submit", body);
 
   [Fact]
   public async Task Below_threshold_without_an_answer_is_rejected_and_stays_a_concept()
@@ -117,7 +117,7 @@ public class IntakeSubmissionTests(TestWebApplicationFactory factory) : IClassFi
 
     // Then the submission is accepted and resolves to Afgewezen — not a 400.
     res.EnsureSuccessStatusCode();
-    var body = (await res.Content.ReadFromJsonAsync<SubmitApplicationResponse>())!;
+    var body = (await res.Content.ReadFromJsonAsync<AanvraagIndienenResponse>())!;
     Assert.Equal("Afgewezen", body.Status.Tag);
   }
 }