feat(example): 添加人脸注册按钮和ID显示功能

- 添加注册按钮，点击生成随机人脸ID（格式：F + 8位数字）
- 实时显示检测到的人脸对应的ID
- 使用彩色标签区分已注册（绿色）和未注册（橙色）状态

Quick task: 260330-ld1

.planning/config.json

@@ -0,0 +1,13 @@
+{
+  "mode": "yolo",
+  "granularity": "standard",
+  "parallelization": true,
+  "commit_docs": true,
+  "model_profile": "balanced",
+  "workflow": {
+    "research": false,
+    "plan_check": false,
+    "verifier": false,
+    "nyquist_validation": false
+  }
+}