feat(instance): 删除实例前备份截图与投影原理图 [GPT-5.6] - #3537

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Nullability of type of parameter 'message' doesn't match overridden member (possibly because of nullability attributes).

Nullability of type of parameter 'message' doesn't match overridden member (possibly because of nullability attributes).

Calling 'ArgumentNullException.ThrowIfNull' and passing a non-nullable value is a no-op (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca2264)

Calling 'ArgumentNullException.ThrowIfNull' and passing a non-nullable value is a no-op (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca2264)