feat(03-03): module loader utility with category page and lazy cards

- Create module-loader.ts with MODULE_REGISTRY mapping slugs to dynamic imports (ssr:false)
- Create [category] page fetching active modules from API, filtering by category
- Create ModuleCard component with icon, name, description, and link to expanded view
- Add i18n keys for modules namespace (de + en)

apps/web/src/messages/en.json

@@ -134,6 +134,14 @@
     "de": "Deutsch",
     "en": "English"
   },
+  "modules": {
+    "categoryTitle": "Modules: {category}",
+    "openModule": "Open",
+    "noModules": "No active modules in this category",
+    "notFound": "Module not found",
+    "notFoundDescription": "The requested module does not exist or is not activated.",
+    "backToCategory": "Back to category"
+  },
   "domaincheck": {
     "title": "Domain Check",
     "description": "Check if a domain is available",