feat(admin): 设备存活监控接口 + 首次无障碍开启时间(first_protected_at) (#80)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---------

Co-authored-by: 陈世睿 <2839904623@qq.com>
Reviewed-on: #80
Co-authored-by: chenshirui <chenshirui@wonderable.ai>
Co-committed-by: chenshirui <chenshirui@wonderable.ai>

app/admin/main.py

@@ -23,6 +23,7 @@ from app.admin.routers.comparison import router as comparison_router
 from app.admin.routers.config import router as config_router
 from app.admin.routers.cps import router as cps_router
 from app.admin.routers.dashboard import router as dashboard_router
+from app.admin.routers.device_liveness import router as device_liveness_router
 from app.admin.routers.ops_stat_config import router as ops_stat_config_router
 from app.admin.routers.feedback import router as feedback_router
 from app.admin.routers.feedback_qr import router as feedback_qr_router
@@ -83,6 +84,7 @@ def health() -> dict[str, str]:
 
 admin_app.include_router(auth_router)
 admin_app.include_router(dashboard_router)
+admin_app.include_router(device_liveness_router)
 admin_app.include_router(ops_stat_config_router)
 admin_app.include_router(ops_marquee_seed_router)
 admin_app.include_router(users_router)