Resolution dropdown, list-focus preservation, unified dark theme, startup logging, and memory map

- Bottom-bar resolution dropdown (1080p60/1080p30/720p60/480p30) with tooltip
  on finding upload bandwidth; disabled while live; no in-app speed test
- FocusPreservingListBox keeps selection/focus coherent when a selected
  scene/source is deleted (skip hidden scenes; leave list when empty)
- Themes/Controls.xaml: single dark-theme dictionary merged once in App.xaml;
  custom ComboBox template fixes SelectionBoxItem rendering; GoLiveWindow and
  ReuseImageDialog consolidated onto shared styles
- AppLog file logger + AppDomain/Dispatcher exception hooks; checkpointed
  MainWindow/VM/dialog constructors (caught MenuItemRole.Separator XAML crash)
- Memory map: schema.md conventions, per-directory index.md, updated ai.md/
  TASKS.md/README.md (OAuth creds real; token persistence still pending)

MainWindow.xaml.cs

@@ -4,6 +4,7 @@ using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Media;
+using ytLive.Helpers;
 using ytLive.Models;
 using ytLive.ViewModels;
 
@@ -15,11 +16,21 @@ public partial class MainWindow : Window
 
     public MainWindow()
     {
+        AppLog.Write("MainWindow ctor: before InitializeComponent");
         InitializeComponent();
+        AppLog.Write("MainWindow ctor: after InitializeComponent");
         _viewModel = (MainViewModel)DataContext;
         _viewModel.PropertyChanged += OnViewModelPropertyChanged;
+        // When a focused scene is deleted, never land focus on a hidden scene.
+        SceneList.IsSelectable = item => item is Scene { IsHidden: false };
         UpdateTaskbarOverlay();
         UpdateSelectionOverlay();
+        AppLog.Write("MainWindow ctor: end");
+    }
+
+    private void MainWindow_Loaded(object sender, RoutedEventArgs e)
+    {
+        AppLog.Write("MainWindow loaded");
     }
 
     private void OnViewModelPropertyChanged(object? sender, PropertyChangedEventArgs e)