Add new namespaces and improve RewriteOptions readability

Added several `using` directives in `Program.cs` for new functionalities and dependencies. Modified `RewriteOptions` configuration to use `HttpStatusCode.MovedPermanently` instead of a hardcoded integer for better readability and maintainability.

src/Moonglade.Web/Program.cs

@@ -1,4 +1,5 @@
 using System.Globalization;
+using System.Net;
 using System.Text.Json.Serialization;
 using Edi.Captcha;
 using Edi.PasswordGenerator;
@@ -286,7 +287,7 @@ private static void ConfigureMiddleware(WebApplication app, List<CultureInfo> cu
             SupportedUICultures = cultures
         });
 
-        var options = new RewriteOptions().AddRedirect(@"(.*)/$", @"\$1", 301);
+        var options = new RewriteOptions().AddRedirect(@"(.*)/$", @"\$1", (int)HttpStatusCode.MovedPermanently);
         app.UseRewriter(options);
         app.UseStaticFiles();
         app.UseSession().UseCaptchaImage(p =>