Refactor project files for improved readability and structure

- Cleaned up whitespace in Directory.Build.props and Directory.Packages.props for consistency.
- Reformatted project file references in PnvPanel.Api.csproj for better clarity.
- Enhanced code readability in various endpoint files by adjusting line breaks and indentation.
- Standardized method signatures and improved formatting in ResultExtensions and multiple endpoint classes for better maintainability.

backend/src/PnvPanel.Application/Auth/Register/RegisterCommand.cs

@@ -3,6 +3,7 @@ using PnvPanel.Application.Common.Models;
 
 namespace PnvPanel.Application.Auth.Register;
 
-public sealed record RegisterCommand(string UserName, string Password) : ICommand<Result<RegisterResult>>;
+public sealed record RegisterCommand(string UserName, string Password)
+    : ICommand<Result<RegisterResult>>;
 
 public sealed record RegisterResult(Guid Id, string UserName);