修复MainActivity停止时CameraX NPE崩溃

1. 升级CameraX版本 1.3.0 → 1.4.1，从根本修复RequestWithCallback.abort() NPE
2. 跳转PayActivity前调用shutdownCamera()，防止in-flight拍照请求触发生命周期异常
3. onResume()顶部增加相机恢复逻辑，通过cameraProviderFuture==null判断是否需要重新初始化
4. shutdownCamera()中将cameraProviderFuture置null，作为相机已停止的可靠标志

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

gradle/libs.versions.toml

@@ -13,7 +13,7 @@ material = "1.10.0"
 activity = "1.8.0"
 constraintlayout = "2.1.4"
 accompanistPermissions = "0.37.3"
-cameraCore = "1.3.0"
+cameraCore = "1.4.1"
 retrofit = "3.0.0"
 okhttp = "4.12.0"
 timber = "5.0.1"