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/App.axaml.cs

@@ -0,0 +1,144 @@
+using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Markup.Xaml;
+using Microsoft.AspNetCore.DataProtection;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using Serilog;
+using OTSSignsOrchestrator.Core.Configuration;
+using OTSSignsOrchestrator.Core.Data;
+using OTSSignsOrchestrator.Core.Services;
+using OTSSignsOrchestrator.Desktop.Services;
+using OTSSignsOrchestrator.Desktop.ViewModels;
+using OTSSignsOrchestrator.Desktop.Views;
+
+namespace OTSSignsOrchestrator.Desktop;
+
+public class App : Application
+{
+    public static IServiceProvider Services { get; private set; } = null!;
+
+    public override void Initialize()
+    {
+        AvaloniaXamlLoader.Load(this);
+    }
+
+    public override void OnFrameworkInitializationCompleted()
+    {
+        var services = new ServiceCollection();
+        ConfigureServices(services);
+        Services = services.BuildServiceProvider();
+
+        // Apply migrations
+        using (var scope = Services.CreateScope())
+        {
+            var db = scope.ServiceProvider.GetRequiredService<XiboContext>();
+            db.Database.Migrate();
+        }
+
+        Log.Information("ApplicationLifetime type: {Type}", ApplicationLifetime?.GetType().FullName ?? "null");
+
+        if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+        {
+            Log.Information("Creating MainWindow...");
+            var vm = Services.GetRequiredService<MainWindowViewModel>();
+            Log.Information("MainWindowViewModel resolved");
+
+            var window = new MainWindow
+            {
+                DataContext = vm
+            };
+
+            desktop.MainWindow = window;
+            Log.Information("MainWindow assigned to lifetime");
+
+            window.Show();
+            window.Activate();
+            Log.Information("MainWindow Show() + Activate() called");
+
+            desktop.ShutdownRequested += (_, _) =>
+            {
+                var ssh = Services.GetService<SshConnectionService>();
+                ssh?.Dispose();
+            };
+        }
+        else
+        {
+            Log.Warning("ApplicationLifetime is NOT IClassicDesktopStyleApplicationLifetime — window cannot be shown");
+        }
+
+        base.OnFrameworkInitializationCompleted();
+    }
+
+    private static void ConfigureServices(IServiceCollection services)
+    {
+        // Configuration
+        var config = new ConfigurationBuilder()
+            .SetBasePath(AppContext.BaseDirectory)
+            .AddJsonFile("appsettings.json", optional: false)
+            .Build();
+
+        services.AddSingleton<IConfiguration>(config);
+
+        // Options
+        services.Configure<GitOptions>(config.GetSection(GitOptions.SectionName));
+        services.Configure<DockerOptions>(config.GetSection(DockerOptions.SectionName));
+        services.Configure<XiboOptions>(config.GetSection(XiboOptions.SectionName));
+        services.Configure<DatabaseOptions>(config.GetSection(DatabaseOptions.SectionName));
+        services.Configure<FileLoggingOptions>(config.GetSection(FileLoggingOptions.SectionName));
+
+        // Logging
+        services.AddLogging(builder =>
+        {
+            builder.ClearProviders();
+            builder.AddSerilog(dispose: true);
+        });
+
+        // Data Protection
+        var keysDir = Path.Combine(
+            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
+            "OTSSignsOrchestrator", "keys");
+        Directory.CreateDirectory(keysDir);
+
+        services.AddDataProtection()
+            .PersistKeysToFileSystem(new DirectoryInfo(keysDir))
+            .SetApplicationName("OTSSignsOrchestrator");
+
+        // Database
+        var connStr = config.GetConnectionString("Default") ?? "Data Source=otssigns-desktop.db";
+        services.AddDbContext<XiboContext>(options => options.UseSqlite(connStr));
+
+        // HTTP
+        services.AddHttpClient();
+        services.AddHttpClient("XiboApi");
+
+        // SSH services (singletons — maintain connections)
+        services.AddSingleton<SshConnectionService>();
+
+        // Docker services via SSH (scoped so they get fresh per-operation context)
+        services.AddTransient<SshDockerCliService>();
+        services.AddTransient<SshDockerSecretsService>();
+        services.AddTransient<IDockerCliService>(sp => sp.GetRequiredService<SshDockerCliService>());
+        services.AddTransient<IDockerSecretsService>(sp => sp.GetRequiredService<SshDockerSecretsService>());
+
+        // Core services
+        services.AddTransient<SettingsService>();
+        services.AddTransient<GitTemplateService>();
+        services.AddTransient<ComposeRenderService>();
+        services.AddTransient<ComposeValidationService>();
+        services.AddTransient<XiboApiService>();
+        services.AddTransient<InstanceService>();
+
+        // ViewModels
+        services.AddTransient<MainWindowViewModel>();
+        services.AddTransient<HostsViewModel>();
+        services.AddTransient<InstancesViewModel>();
+        services.AddTransient<CreateInstanceViewModel>();
+        services.AddTransient<SecretsViewModel>();
+        services.AddTransient<SettingsViewModel>();
+        services.AddTransient<LogsViewModel>();
+    }
+}