fix: localize home announcement create button

Replace the hardcoded "Create" label on the home announcements section with a dedicated i18n key. Add create_announcement translations for both zh-CN and en-US to keep action labels consistent and explicit.

Author: Vanilla-Yukirin

frontend/src/locales/en.json

@@ -55,6 +55,7 @@
   "contest_ended": "Contest Ended",
   "contests": "Contests",
   "create": "Create",
+  "create_announcement": "Create Announcement",
   "create_contest": "Create Contest",
   "create_discussion": "Create Discussion",
   "create_group": "Create Group",

frontend/src/locales/zh.json

@@ -55,6 +55,7 @@
   "contest_ended": "比赛已结束",
   "contests": "比赛",
   "create": "创建",
+  "create_announcement": "创建公告",
   "create_contest": "创建比赛",
   "create_discussion": "创建讨论",
   "create_group": "创建群组",

frontend/src/views/Home.vue

@@ -78,7 +78,7 @@ onRouteQueryUpdate(fetch)
         </div>
 
         <RouterLink v-if="isAdmin" :to="{ name: 'newsCreate' }">
-          <Button icon="pi pi-plus" label="Create" />
+          <Button icon="pi pi-plus" :label="t('ptoj.create_announcement')" />
         </RouterLink>
       </div>