fix: narrow parseBrpAddress's return type instead of leaking the DTO

BrpAddressDto's fields are generated as optional, so returning it
directly from parseBrpAddress lost the narrowing the runtime check
already did. This broke the build once registratie-lookup.store.ts
assigned the parsed address into a stricter local type. Map to a
proper BrpAddress domain shape at the trust boundary instead.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/ssp/src/app/registratie/application/registratie-lookup.store.ts

@@ -41,7 +41,7 @@ export class RegistratieLookupStore {
       const json = this.adresRes.value();
       if (json === undefined) return null;
       const parsed = parseBrpAddress(json);
-      return parsed.ok && parsed.value.gevonden && parsed.value.adres ? parsed.value.adres : null;
+      return parsed.ok && parsed.value.adres ? parsed.value.adres : null;
     },
   );