feat(search): include user profiles in global search results

Add users group to global search API and frontend types
Query users by display name and link to their public profiles
Update system wordings for the new search group

frontend/src/components/GlobalSearch.vue

@@ -36,7 +36,8 @@ const groupLabels: Record<GlobalSearchGroupType, string> = {
   'ancient-artifacts': 'search.groups.ancientArtifacts',
   recipes: 'search.groups.recipes',
   'daily-checklist': 'search.groups.dailyChecklist',
-  life: 'search.groups.life'
+  life: 'search.groups.life',
+  users: 'search.groups.users'
 };
 
 function clearSearchTimeout() {

frontend/src/services/api.ts

@@ -325,7 +325,8 @@ export type GlobalSearchGroupType =
   | 'ancient-artifacts'
   | 'recipes'
   | 'daily-checklist'
-  | 'life';
+  | 'life'
+  | 'users';
 
 export interface GlobalSearchItem {
   id: number;