feat(portal-self-service): implement the DigiD registration submit page (refs #67)

RegistrationPage shows the signed-in BSN and submits to the BFF via the generated
api-client, confirming with the returned reference; built from NL Design System
(Utrecht) components. Wire the guarded route + app providers (DigiD OIDC + token
interceptor + HttpClient), the NL DS theme, and lang=nl. Component tests
(Testing Library) + axe (WCAG 2.1 AA) pass; a guard test covers libs/auth. Replace
the demo eslint depConstraints (scope:shop/shared) with a permissive default.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

eslint.config.mjs

@@ -19,22 +19,12 @@ export default [
         {
           enforceBuildableLibDependency: true,
           allow: ['^.*/eslint(\\.base)?\\.config\\.[cm]?[jt]s$'],
+          // Permissive default — apps/libs are untagged for now. Introduce scope/type tags
+          // when the portal set grows (docs/frontend-decisions.md).
           depConstraints: [
             {
-              sourceTag: 'scope:shared',
-              onlyDependOnLibsWithTags: ['scope:shared'],
-            },
-            {
-              sourceTag: 'scope:shop',
-              onlyDependOnLibsWithTags: ['scope:shop', 'scope:shared'],
-            },
-            {
-              sourceTag: 'scope:api',
-              onlyDependOnLibsWithTags: ['scope:api', 'scope:shared'],
-            },
-            {
-              sourceTag: 'type:data',
-              onlyDependOnLibsWithTags: ['type:data'],
+              sourceTag: '*',
+              onlyDependOnLibsWithTags: ['*'],
             },
           ],
         },