feat: redesign Big Screen voting view with philatelic postcard UI

- Add PostcardItem.vue component with Chinese postal aesthetics
- Add PostcardGrid.vue container with 4x2 CSS Grid layout
- Add Postmark.vue component for real-time vote stamp visualization
- Update LiveVotingView.vue with cream paper theme (#FDFBF7)
- Add Year of the Horse 2026 stamp image
- Add responsive breakpoints for different screen sizes
- Enhance admin service with program voting control
- Add vote stamp accumulation for big screen display

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/client-mobile/src/views/HomeView.vue

@@ -8,6 +8,7 @@ const router = useRouter();
 const connectionStore = useConnectionStore();
 
 const userName = ref('');
+const userDept = ref('技术部');
 const isLoading = ref(false);
 
 async function handleEnter() {
@@ -21,7 +22,7 @@ async function handleEnter() {
   // Generate a simple user ID (in production, this would come from auth)
   const odrawId = `user_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`;
 
-  connectionStore.setUser(odrawId, userName.value.trim());
+  connectionStore.setUser(odrawId, userName.value.trim(), userDept.value);
 
   // Wait for connection
   await new Promise((resolve) => setTimeout(resolve, 500));
@@ -61,6 +62,17 @@ async function handleEnter() {
             @keyup.enter="handleEnter"
           />
         </div>
+ 
+        <div class="input-wrapper guochao-border">
+          <van-field
+            v-model="userDept"
+            placeholder="请输入您的部门"
+            :border="false"
+            clearable
+            maxlength="20"
+            @keyup.enter="handleEnter"
+          />
+        </div>
 
         <van-button
           class="enter-btn"