Fix Mijn aanvragen: instant cancel + one Concept per type (resume)

Two dashboard bugs from the just-built feature.

1. Cancel didn't reflect until a browser refresh. ApplicationsStore now OWNS the
   list in a writable RemoteData signal instead of projecting a resource() through
   fromResource; cancel removes the row synchronously (guaranteed disappear, no
   dependence on CD timing / HTTP cache / the reloading gap), then confirms the
   DELETE (rollback on failure, no resync). Adapter gains list(); applicationsResource()
   removed. Shared fromResource/remote-data.ts deliberately untouched.

2. Duplicate / inconsistent Concepts per type. createDraftSync.resume() now: a
   ?aanvraag link wins; else it resumes THIS type's existing Concept (loads its
   draft); else fresh. ensureId is gated behind resume so a fast typist can't create
   a duplicate before the lookup lands. restart()/reset() deletes the current Concept
   (submitted → 409, kept) so there's at most one active Concept per type. A non-Concept
   id can't reopen as an editable draft. Backend unchanged.

Gates green: lint, vitest 128, build, check:tokens, backend dotnet 56.
Wiring is not unit-covered — needs live verification (see plan).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/registratie/ui/registratie-wizard/registratie-wizard.component.ts

@@ -375,7 +375,7 @@ export class RegistratieWizardComponent {
   /** Reset the wizard to a fresh start. Reload the BRP lookup so the address
       re-prefills, keeping the form and the "vooraf ingevuld" note consistent. */
   restart() {
-    this.draftSync.reset(); // detach from the old Concept; next progress creates a new one
+    this.draftSync.reset(); // discard the current Concept; a fresh one starts on next progress
     this.dispatch({ tag: 'Seed', state: initial });
     this.adresRes.reload();
   }