fix(quick-search): Esc closes only the modal; cancel returns focus to target

- The qsInput Esc handler didn't stopPropagation, so the SAME keystroke fell
  through to the document-level Esc handlers which, seeing the modal now
  closed, also closed (or discard-prompted) the dirty slideover behind it.
- autofill/cancel now hands the foreground back to the saved target HWND:
  Esc after a fill-mode hotkey returns the user to the window they came
  from instead of leaving our app focused. Locked-vault path still ends
  focused on us (cancelAutofill runs before focusApp).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

js/app.js

@@ -7964,6 +7964,10 @@ async function init() {
             const rows = document.querySelectorAll('#quickSearchResults .quick-search-row');
             if (e.key === 'Escape') {
                 e.preventDefault();
+                // Kill the keystroke: without this the SAME Esc reaches the
+                // document-level handlers, which now see "no modal open"
+                // (we just closed it) and also close the dirty slideover.
+                e.stopPropagation();
                 closeQuickSearchModal();
             } else if (e.key === 'ArrowDown') {
                 e.preventDefault();