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/contracts/brp-address.dto.ts

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+/**
+ * WIRE CONTRACT for the BRP address lookup ("BFF-lite" — one screen-shaped call).
+ *
+ * In production this is GENERATED from the OpenAPI/TypeSpec spec and served by our
+ * own backend, which talks to the BRP behind an adapter. The frontend never sees
+ * the BRP's own wire format. See docs/architecture/0001-bff-lite-decision-dtos.md.
+ *
+ * "Geen adres bekend" is a first-class outcome (`gevonden: false`), not an error —
+ * the wizard falls back to manual entry (PRD §7). Slice 1 ships only the happy
+ * path (gevonden: true).
+ */
+export interface BrpAddressDto {
+  gevonden: boolean;
+  adres?: { straat: string; postcode: string; woonplaats: string };
+}

src/app/registratie/contracts/dashboard-view.dto.ts

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+import { Registration } from '@registratie/domain/registration';
+import { Person } from '@registratie/domain/person';
+import { BigProfile } from '@registratie/domain/big-profile';
+
+/**
+ * WIRE CONTRACT for the dashboard screen — the "BFF-lite" response.
+ *
+ * In production this type is GENERATED from the OpenAPI/TypeSpec spec (one source
+ * of truth for both sides), and the `decisions` block is computed BY THE BACKEND
+ * — never recomputed on the client. The frontend renders decisions; it does not
+ * own the rules. See docs/architecture/0001-bff-lite-decision-dtos.md.
+ *
+ * One screen-shaped call replaces the previous three (BIG-register + BRP + …),
+ * so the page always sees one consistent snapshot instead of three independently
+ * loading/erroring resources.
+ */
+export interface DashboardViewDto {
+  registration: Registration;
+  person: Person;
+  decisions: HerregistratieDecisions;
+}
+
+/** Server-computed decisions. The eligibility rule lives on the backend; the
+    optional reason lets the UI explain itself without knowing the rule. */
+export interface HerregistratieDecisions {
+  eligibleForHerregistratie: boolean;
+  herregistratieReason?: string;
+}
+
+/** The parsed, frontend-side view (DTO mapped onto our own domain model). Keeping
+    this distinct from DashboardViewDto is the decoupling seam: the wire shape can
+    change without the FE domain following, and vice-versa. */
+export interface DashboardView {
+  profile: BigProfile;
+  decisions: HerregistratieDecisions;
+}

src/app/registratie/contracts/duo-diplomas.dto.ts

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+/**
+ * WIRE CONTRACT for the DUO diploma lookup ("BFF-lite" — one screen-shaped call
+ * returning everything the beroep step needs).
+ *
+ * Each diploma carries its server-computed `beroep` (the profession it maps to)
+ * and the `policyQuestions` (geldigheidsvragen) that apply to it. These are
+ * DECISIONS computed by the backend from the diploma's attributes — the frontend
+ * renders them, it does not derive them (decision-DTO pattern, ADR-0001). E.g. an
+ * English-language diploma carries the Dutch-proficiency question.
+ *
+ * `handmatig` is the fallback when the diploma is not in the DUO list: the
+ * professions the user may declare and the MAXIMAL policy-question set that then
+ * applies (a manual diploma is unverified, so the strictest set is used).
+ */
+export interface DuoLookupDto {
+  diplomas: DuoDiplomaDto[];
+  handmatig: ManualDiplomaPolicyDto;
+}
+
+export interface DuoDiplomaDto {
+  id: string;
+  naam: string;
+  instelling: string;
+  jaar: number;
+  beroep: string; // server-derived profession
+  policyQuestions: PolicyQuestionDto[]; // server-decided geldigheidsvragen
+}
+
+export interface ManualDiplomaPolicyDto {
+  beroepen: string[]; // professions the user may declare for a manual diploma
+  policyQuestions: PolicyQuestionDto[]; // maximal set applied to a manual diploma
+}
+
+export interface PolicyQuestionDto {
+  id: string;
+  vraag: string;
+  type: 'ja-nee' | 'tekst';
+}