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/infrastructure/duo.adapter.ts

@@ -0,0 +1,60 @@
+import { Injectable } from '@angular/core';
+import { httpResource } from '@angular/common/http';
+import { Result, ok, err } from '@shared/kernel/fp';
+import { DuoLookupDto, DuoDiplomaDto, PolicyQuestionDto, ManualDiplomaPolicyDto } from '@registratie/contracts/duo-diplomas.dto';
+
+const EMPTY: DuoLookupDto = { diplomas: [], handmatig: { beroepen: [], policyQuestions: [] } };
+
+/**
+ * Infrastructure adapter for the DUO diploma lookup, reached only through our own
+ * ("BFF-lite") endpoint — the anti-corruption boundary. The response carries the
+ * user's diplomas (each with its server-computed beroep + policy questions) and
+ * the manual-entry fallback policy. The frontend renders; it does not derive. In
+ * this POC the endpoint is a static mock.
+ */
+@Injectable({ providedIn: 'root' })
+export class DuoAdapter {
+  diplomasResource() {
+    return httpResource<DuoLookupDto>(() => 'mock/duo-diplomas.json', { defaultValue: EMPTY });
+  }
+}
+
+function parseQuestions(json: unknown): PolicyQuestionDto[] | null {
+  if (!Array.isArray(json)) return null;
+  const out: PolicyQuestionDto[] = [];
+  for (const q of json) {
+    if (typeof q !== 'object' || q === null) return null;
+    const p = q as Partial<PolicyQuestionDto>;
+    if (typeof p.id !== 'string' || typeof p.vraag !== 'string' || (p.type !== 'ja-nee' && p.type !== 'tekst')) return null;
+    out.push({ id: p.id, vraag: p.vraag, type: p.type });
+  }
+  return out;
+}
+
+/** Trust-boundary parse: validate the untrusted response shape (diplomas, each
+    with derived beroep + policy questions, plus the manual-entry fallback). */
+export function parseDuoLookup(json: unknown): Result<string, DuoLookupDto> {
+  if (typeof json !== 'object' || json === null) return err('duo-lookup: not an object');
+  const dto = json as Partial<DuoLookupDto>;
+  if (!Array.isArray(dto.diplomas)) return err('duo-lookup: missing diplomas');
+
+  const diplomas: DuoDiplomaDto[] = [];
+  for (const item of dto.diplomas) {
+    if (typeof item !== 'object' || item === null) return err('duo-lookup: invalid diploma');
+    const d = item as Partial<DuoDiplomaDto>;
+    const vragen = parseQuestions(d.policyQuestions);
+    if (typeof d.id !== 'string' || typeof d.naam !== 'string' || typeof d.beroep !== 'string' || vragen === null) {
+      return err('duo-lookup: missing/invalid diploma fields');
+    }
+    diplomas.push({ id: d.id, naam: d.naam, instelling: d.instelling ?? '', jaar: typeof d.jaar === 'number' ? d.jaar : 0, beroep: d.beroep, policyQuestions: vragen });
+  }
+
+  const hm = dto.handmatig;
+  const hmVragen = hm ? parseQuestions(hm.policyQuestions) : null;
+  if (!hm || !Array.isArray(hm.beroepen) || hmVragen === null) {
+    return err('duo-lookup: missing/invalid handmatig fallback');
+  }
+  const handmatig: ManualDiplomaPolicyDto = { beroepen: hm.beroepen, policyQuestions: hmVragen };
+
+  return ok({ diplomas, handmatig });
+}