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)

ReuseImageDialog.xaml.cs

@@ -1,4 +1,5 @@
 using System.Windows;
+using ytLive.Helpers;
 using ytLive.ViewModels;
 
 namespace ytLive;
@@ -10,7 +11,9 @@ public partial class ReuseImageDialog : Window
 
     public ReuseImageDialog(ReuseImageViewModel viewModel)
     {
+        AppLog.Write("ReuseImageDialog ctor: before InitializeComponent");
         InitializeComponent();
+        AppLog.Write("ReuseImageDialog ctor: after InitializeComponent");
         DataContext = viewModel;
         viewModel.ReuseRequested += () =>
         {