fix(dialog): improve escape key handling for dialogs

The handling of the Escape key has been refined to ensure that it
closes the correct dialog based on the current state. Additionally,
the z-index for the compare dialog backdrop has been updated to
ensure proper layering with other dialogs.

- Enhanced Escape key functionality for better user experience
- Updated z-index for compare dialog backdrop to avoid overlap

src/app.css

@@ -2882,6 +2882,7 @@
     overflow: hidden;
   }
   .file-history-dialog-backdrop { z-index: 70; }
+  .compare-dialog-backdrop { z-index: 80; }
   .file-history-dialog {
     display: grid;
     grid-template-rows: auto minmax(0, 1fr);