feat(fp): WP-05 — parse-don't-validate closure + MDX

Close the three remaining unvalidated `as <DomainType>` casts at the wire
boundary (intake-policy, big-register aantekening type, brief passage scope),
each replaced by a Result-returning parser with a rejection-case spec, plus
the Foundations/Parse, don't validate curriculum page.

src/app/brief/infrastructure/brief.adapter.spec.ts

@@ -141,6 +141,14 @@ describe('brief.adapter parse boundary', () => {
     ]);
   });
 
+  it('rejects a library passage with an unknown scope', () => {
+    const r = parseBriefView({
+      ...view,
+      availablePassages: [{ ...view.availablePassages![0], scope: 'bogus' as never }],
+    });
+    expect(r.ok).toBe(false);
+  });
+
   it('rejects a passage block missing provenance', () => {
     const r = parseBrief({
       ...view.brief,

src/app/brief/infrastructure/brief.adapter.ts

@@ -21,7 +21,6 @@ import {
   LetterBlock,
   LetterSection,
   LibraryPassage,
-  PassageScope,
 } from '@brief/domain/brief';
 import { PlaceholderDef } from '@brief/domain/placeholders';
 import { Mark, Paragraph, RichTextBlock, RichTextNode } from '@shared/kernel/rich-text';
@@ -228,8 +227,9 @@ export function parseStatus(dto: BriefStatusDto | undefined): Result<string, Bri
 }
 
 function parsePassage(dto: LibraryPassageDto): Result<string, LibraryPassage> {
-  if (typeof dto.passageId !== 'string' || (dto.scope !== 'global' && dto.scope !== 'beroep'))
-    return err('passage: bad shape');
+  if (typeof dto.passageId !== 'string') return err('passage: bad shape');
+  if (dto.scope !== 'global' && dto.scope !== 'beroep')
+    return err(`passage: unknown scope ${dto.scope}`);
   if (
     typeof dto.sectionKey !== 'string' ||
     typeof dto.label !== 'string' ||
@@ -240,7 +240,7 @@ function parsePassage(dto: LibraryPassageDto): Result<string, LibraryPassage> {
   if (!content.ok) return content;
   return ok({
     passageId: dto.passageId,
-    scope: dto.scope as PassageScope,
+    scope: dto.scope,
     sectionKey: dto.sectionKey,
     label: dto.label,
     content: content.value,