fix(Appearance Settings): No default welcome message or description is provided.

frontend/src/stores/appearance.ts

@@ -67,8 +67,8 @@ export const useAppearanceStore = defineStore('appearanceStore', {
       showDemoTips: false,
       demoTipsContent: '',
       fontList: [],
-      pc_welcome: '',
-      pc_welcome_desc: '',
+      pc_welcome: undefined,
+      pc_welcome_desc: undefined,
     }
   },
   getters: {

frontend/src/views/chat/index.vue

@@ -145,10 +145,10 @@
                   ><custom_small v-if="appearanceStore.themeColor !== 'default'"></custom_small>
                   <LOGO_fold v-else></LOGO_fold
                 ></el-icon>
-                {{ appearanceStore.pc_welcome }}
+                {{ appearanceStore.pc_welcome ?? t('qa.greeting') }}
               </div>
               <div class="sub">
-                {{ appearanceStore.pc_welcome_desc }}
+                {{ appearanceStore.pc_welcome_desc ?? t('qa.hint_description') }}
               </div>
             </template>