Restructures project with feature-based organization

Refactors project structure to support modular, feature-driven development

Introduces comprehensive language localization support
Adds menu management with role-based access control
Implements dynamic sidebar and theme switching capabilities

Enhances project scalability and maintainability

app/Controllers/HomeController.cs

@@ -0,0 +1,12 @@
+using Microsoft.AspNetCore.Mvc;
+
+namespace CalendarServer.Controllers;
+
+public class HomeController : Controller
+{
+    public IActionResult Index()
+    {
+        ViewData["Title"] = "Dashboard";
+        return View();
+    }
+}