feat: implement QR code scan login system with admin control

- Add scan login service with Redis-based token management
- Add scan login API routes for token generation and validation
- Add QRCodeLogin component for PC-side QR code display
- Add EntryQRCode component for mass login scenarios
- Add ScanLoginView for mobile-side login form
- Add localStorage persistence for user identity
- Add logout functionality to mobile client
- Add auto-redirect for logged-in users
- Add admin console control for QR code display on big screen
- Add socket event forwarding from admin to screen display

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

packages/client-screen/src/views/AdminControl.vue

@@ -243,6 +243,21 @@ function playFanfare() {
   admin.controlMusic('play', 'fanfare');
 }
 
+// QR Code display control
+function showEntryQR() {
+  const socket = admin.getSocket();
+  if (socket) {
+    socket.emit('display:show_entry_qr' as any, {});
+  }
+}
+
+function hideQR() {
+  const socket = admin.getSocket();
+  if (socket) {
+    socket.emit('display:hide_qr' as any, );
+  }
+}
+
 // Computed helpers
 const currentPrizeConfig = computed(() => {
   // 优先使用从服务器加载的配置
@@ -666,6 +681,19 @@ onMounted(() => {
             </div>
           </div>
 
+          <!-- QR Code Display Control -->
+          <div class="control-group">
+            <h4>大屏二维码</h4>
+            <div class="button-group">
+              <button class="ctrl-btn primary" @click="showEntryQR">
+                显示入场二维码
+              </button>
+              <button class="ctrl-btn outline" @click="hideQR">
+                隐藏二维码
+              </button>
+            </div>
+          </div>
+
           <!-- Music Control -->
           <div class="control-group">
             <h4>音乐控制</h4>