feat: Add main application views and structure

- Implemented CreateInstanceView for creating new instances.
- Added HostsView for managing SSH hosts with CRUD operations.
- Created InstancesView for displaying and managing instances.
- Developed LogsView for viewing operation logs.
- Introduced SecretsView for managing secrets associated with hosts.
- Established SettingsView for configuring application settings.
- Created MainWindow as the main application window with navigation.
- Added app manifest and configuration files for logging and settings.

OTSSignsOrchestrator.Desktop/Program.cs

@@ -0,0 +1,40 @@
+using Avalonia;
+using Avalonia.ReactiveUI;
+using Microsoft.Extensions.DependencyInjection;
+using Serilog;
+using System;
+
+namespace OTSSignsOrchestrator.Desktop;
+
+sealed class Program
+{
+    [STAThread]
+    public static void Main(string[] args)
+    {
+        Log.Logger = new LoggerConfiguration()
+            .MinimumLevel.Debug()
+            .WriteTo.Console()
+            .WriteTo.File("logs/app-.log", rollingInterval: RollingInterval.Day, retainedFileCountLimit: 7)
+            .CreateLogger();
+
+        try
+        {
+            BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
+        }
+        catch (Exception ex)
+        {
+            Log.Fatal(ex, "Application terminated unexpectedly");
+        }
+        finally
+        {
+            Log.CloseAndFlush();
+        }
+    }
+
+    public static AppBuilder BuildAvaloniaApp()
+        => AppBuilder.Configure<App>()
+            .UsePlatformDetect()
+            .WithInterFont()
+            .LogToTrace()
+            .UseReactiveUI();
+}