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/src/BigRegister.Api/Domain/Intake/IntakePolicy.cs

@@ -6,7 +6,7 @@ namespace BigRegister.Domain.Intake;
 /// (<c>GET /intake/policy</c>) and applies it for instant UX feedback
 /// (<c>intake.machine.ts</c>'s <c>lageUren</c>); <see cref="RejectIncompleteScholing"/> is the
 /// backend re-validating it as the authority on submit (WP-69) —
-/// <c>POST /applications/{id}/submit</c> (intake-typed aanvragen only) calls it before
+/// <c>POST /aanvragen/{id}/submit</c> (intake-typed aanvragen only) calls it before
 /// writing anything, and a violation 400s (<c>ProblemDetails</c>), never silently accepts
 /// an incomplete answer.
 /// </summary>