feat: add remove, list, and add config commands

src/AltGen.Console/Config/ListConfigCommand.cs

@@ -0,0 +1,34 @@
+
+namespace AltGen.Console.Config;
+
+sealed class ListConfigCommand(IAnsiConsole console, IFileSystem fileSystem) : AsyncCommand
+{
+  readonly IAnsiConsole _console = console;
+  readonly IFileSystem _fileSystem = fileSystem;
+
+  public override async Task<int> ExecuteAsync(CommandContext context)
+  {
+    var settingsPath = _fileSystem.Path.Combine(AppContext.BaseDirectory, AppSettings.SettingsFileName);
+    var settingsExist = _fileSystem.File.Exists(settingsPath);
+
+    if (settingsExist is false)
+    {
+      _console.MarkupLine("No settings found.");
+      return 0;
+    }
+
+    var settingsJson = await _fileSystem.File.ReadAllTextAsync(settingsPath);
+    var appSettings = JsonSerializer.Deserialize<AppSettings>(settingsJson, JsonOptions.Default)
+      ?? throw new ConfigException("Failed to deserialize settings.");
+
+    foreach (var provider in appSettings.Providers)
+    {
+      var providerName = provider.Provider;
+      var providerKey = provider.Key;
+      var isDefault = provider.Default ? " (default)" : string.Empty;
+      _console.MarkupLine($"[bold]{providerName}[/] [dim]{providerKey}[/]{isDefault}");
+    }
+
+    return 0;
+  }
+}