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.Infrastructure/Persistence/AppDbContext.cs

@@ -19,7 +19,8 @@ namespace PnvPanel.Infrastructure.Persistence;
 /// (добавляются по мере реализации фич, см. docs/roadmap.md).
 /// </summary>
 public class AppDbContext(DbContextOptions<AppDbContext> options)
-    : IdentityDbContext<AppUser, AppRole, Guid>(options), IAppDbContext
+    : IdentityDbContext<AppUser, AppRole, Guid>(options),
+        IAppDbContext
 {
     public DbSet<RefreshToken> RefreshTokens => Set<RefreshToken>();