Add news feature with CRUD operations and real-time notifications

- Implemented news management functionality, allowing admins to create, read, update, and delete news posts.
- Introduced a new SignalR event for broadcasting news updates to all connected clients.
- Updated API documentation to include new endpoints for news management.
- Enhanced frontend with a dedicated news page and admin interface for managing news posts.
- Added necessary localization for news-related terms in both Russian and English.

backend/src/PnvPanel.Api/Endpoints/NewsEndpoints.cs

@@ -0,0 +1,24 @@
+using PnvPanel.Api.Common;
+using PnvPanel.Application.Common.Messaging;
+using PnvPanel.Application.Common.Models;
+using PnvPanel.Application.News;
+
+namespace PnvPanel.Api.Endpoints;
+
+public static class NewsEndpoints
+{
+    public static IEndpointRouteBuilder MapNewsEndpoints(this IEndpointRouteBuilder app)
+    {
+        app.MapGet("/api/news", ListNews)
+            .WithTags("News")
+            .RequireAuthorization()
+            .Produces<PagedList<NewsPostDto>>();
+        return app;
+    }
+
+    private static async Task<IResult> ListNews(int page, int pageSize, ISender sender, CancellationToken cancellationToken)
+    {
+        var result = await sender.Send(new ListNewsQuery(page, pageSize), cancellationToken);
+        return result.ToHttpResult();
+    }
+}