feat(web): vocabularies two-pane screen (list/create + terms/add) + nav

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/i18n/en.json

@@ -8,6 +8,12 @@
   "form": { "selectPlaceholder": "— select —", "create": "Create object", "save": "Save", "cancel": "Cancel", "visibility": "Visibility", "draft": "Draft", "internal": "Internal", "required": "This field is required", "rejected": "The server rejected the changes — check required and referenced fields", "flexibleHeading": "Catalogue fields" },
   "actions": { "edit": "Edit", "delete": "Delete", "confirmDelete": "Delete this object? This cannot be undone." },
   "labels": { "en": "Label (EN)", "sv": "Label (SV)", "externalUri": "External URI (optional)" },
+  "vocab": {
+    "title": "Vocabularies", "newVocabulary": "New vocabulary", "key": "Key",
+    "create": "Create", "selectPrompt": "Select a vocabulary to manage its terms",
+    "terms": "Terms", "addTerm": "Add term", "empty": "No vocabularies yet",
+    "noTerms": "No terms yet", "loadError": "Could not load"
+  },
   "publish": {
     "heading": "Visibility",
     "advanceInternal": "Advance to internal",