Add registratie wizard, BFF dashboard-view, contracts/value-objects, and architecture docs

Checkpoint of in-progress work: the registration wizard (address prefill,
DUO diploma lookup, policy questions), decision-DTO contracts, parse-don't-
validate value objects, infrastructure adapters, plus CLAUDE.md and the
architecture/ADR docs.

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

src/app/registratie/ui/dashboard.page.ts

@@ -56,6 +56,9 @@ import { BigProfileStore } from '@registratie/application/big-profile.store';
       </div>
 
       <p style="margin-top:2rem">
+        <app-link to="/registreren">Inschrijven in het BIG-register (registratiewizard) →</app-link>
+      </p>
+      <p>
         <app-link to="/registratie">Gegevens bekijken of een wijziging doorgeven →</app-link>
       </p>
       <p>