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.Infrastructure/Persistence/Migrations/AppDbContextModelSnapshot.cs

@@ -394,6 +394,35 @@ namespace PnvPanel.Infrastructure.Persistence.Migrations
                     b.ToTable("Inbounds", (string)null);
                 });
 
+            modelBuilder.Entity("PnvPanel.Domain.News.NewsPost", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uuid");
+
+                    b.Property<string>("Body")
+                        .IsRequired()
+                        .HasMaxLength(20000)
+                        .HasColumnType("character varying(20000)");
+
+                    b.Property<DateTimeOffset>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("Title")
+                        .IsRequired()
+                        .HasMaxLength(200)
+                        .HasColumnType("character varying(200)");
+
+                    b.Property<DateTimeOffset?>("UpdatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CreatedAt");
+
+                    b.ToTable("NewsPosts", (string)null);
+                });
+
             modelBuilder.Entity("PnvPanel.Domain.Nodes.Node", b =>
                 {
                     b.Property<Guid>("Id")