test(portal-openbaar): drive the openbaar register page — list, search, empty state (refs #10)

Scaffolds the anonymous openbaar Angular app (mirrors self-service: standalone +
signals, NL DS via the ui lib, no auth) and adds a failing register-page spec:
loads the public register from the BFF on open, searches by term, and shows an
empty-state message. The stub page renders only the heading, so the list/search/
empty-state assertions fail (red).

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

apps/openbaar/eslint.config.mjs

@@ -0,0 +1,34 @@
+import nx from '@nx/eslint-plugin';
+import baseConfig from '../../eslint.config.mjs';
+
+export default [
+  ...nx.configs['flat/angular'],
+  ...nx.configs['flat/angular-template'],
+  ...baseConfig,
+  {
+    files: ['**/*.ts'],
+    rules: {
+      '@angular-eslint/directive-selector': [
+        'error',
+        {
+          type: 'attribute',
+          prefix: 'app',
+          style: 'camelCase',
+        },
+      ],
+      '@angular-eslint/component-selector': [
+        'error',
+        {
+          type: 'element',
+          prefix: 'app',
+          style: 'kebab-case',
+        },
+      ],
+    },
+  },
+  {
+    files: ['**/*.html'],
+    // Override or add rules here
+    rules: {},
+  },
+];