feat: Add Instance Details ViewModel and UI for managing instance credentials

- Introduced InstanceDetailsViewModel to handle loading and displaying instance-specific credentials.
- Created InstanceDetailsWindow and associated XAML for displaying admin, database, and OAuth2 credentials.
- Updated InstancesViewModel to include command for opening instance details.
- Enhanced SettingsViewModel to manage Bitwarden and Xibo Bootstrap configurations, including connection testing.
- Added UI components for Bitwarden Secrets Manager and Xibo Bootstrap OAuth2 settings in the SettingsView.
- Implemented password visibility toggles and clipboard copy functionality for sensitive information.

OTSSignsOrchestrator.Desktop/ViewModels/InstancesViewModel.cs

@@ -30,6 +30,9 @@ public partial class InstancesViewModel : ObservableObject
     [ObservableProperty] private ObservableCollection<SshHost> _availableHosts = new();
     [ObservableProperty] private SshHost? _selectedSshHost;
 
+    /// <summary>Raised when the instance details modal should be opened for the given ViewModel.</summary>
+    public event Action<InstanceDetailsViewModel>? OpenDetailsRequested;
+
     public InstancesViewModel(IServiceProvider services)
     {
         _services = services;
@@ -158,4 +161,29 @@ public partial class InstancesViewModel : ObservableObject
         catch (Exception ex) { StatusMessage = $"Error rotating password: {ex.Message}"; }
         finally { IsBusy = false; }
     }
+
+    [RelayCommand]
+    private async Task OpenDetailsAsync()
+    {
+        if (SelectedInstance == null) return;
+
+        IsBusy = true;
+        StatusMessage = $"Loading details for '{SelectedInstance.StackName}'...";
+        try
+        {
+            // Set the SSH host on singleton Docker services so modal operations target the right host
+            var dockerCli = _services.GetRequiredService<SshDockerCliService>();
+            dockerCli.SetHost(SelectedInstance.Host);
+            var dockerSecrets = _services.GetRequiredService<SshDockerSecretsService>();
+            dockerSecrets.SetHost(SelectedInstance.Host);
+
+            var detailsVm = _services.GetRequiredService<InstanceDetailsViewModel>();
+            await detailsVm.LoadAsync(SelectedInstance);
+
+            OpenDetailsRequested?.Invoke(detailsVm);
+            StatusMessage = string.Empty;
+        }
+        catch (Exception ex) { StatusMessage = $"Error opening details: {ex.Message}"; }
+        finally { IsBusy = false; }
+    }
 }