feat: add page shell, preferences and translations

Base layout with top bar, role-based menu, profile menu and phone layout; theme, language and German form of address kept in cookies; German formal, German informal and English text; Fluent avatar bundled in the image by a Node build stage; placeholder pages for the Publisher and Admin groups.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N3t4WL7bd9bdHHNjEsxzqC

portal/frontend/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "portal-frontend",
+  "version": "0.1.0",
+  "private": true,
+  "description": "Builds the Fluent web components bundle that is copied into the image.",
+  "type": "module",
+  "scripts": {
+    "build": "node build.mjs"
+  },
+  "dependencies": {
+    "@fluentui/web-components": "3.1.3"
+  },
+  "devDependencies": {
+    "esbuild": "0.28.2"
+  }
+}