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/Directory.Build.props

@@ -1,5 +1,4 @@
 <Project>
-
   <PropertyGroup>
     <TargetFramework>net10.0</TargetFramework>
     <LangVersion>latest</LangVersion>
@@ -18,5 +17,4 @@
     -->
     <NoWarn>$(NoWarn);CA1711;CA1716;CA1848;CA1873</NoWarn>
   </PropertyGroup>
-
 </Project>