fix: rename node not found, A11y warnings cleanup

- fix renameId cleared before RenameNode API call (submitRename)
- add role, tabindex, keydown handlers to all interactive divs
- associate labels with inputs (wrap in label + .label-text)
- remove autofocus, unused CSS selectors, old root build.sh
- update frontend-dist assets

frontend/src/lib/ConfirmModal.svelte

@@ -10,7 +10,7 @@
   const dispatch = createEventDispatcher()
 </script>
 
-<div class="overlay" on:click|self={() => dispatch('cancel')} role="dialog" aria-modal="true" aria-label={title}>
+<div class="overlay" on:click|self={() => dispatch('cancel')} on:keydown={(e) => { if (e.key === 'Escape') { e.preventDefault(); dispatch('cancel') } }} role="presentation">
   <div class="modal">
     <h3>{title}</h3>
     <p class="message">{message}</p>

frontend/src/lib/FilePreviewModal.svelte

@@ -35,7 +35,7 @@
   })
 </script>
 
-<div class="overlay" on:click|self={() => dispatch('close')} role="dialog" aria-modal="true" aria-label={`Preview: ${item.name}`}>
+<div class="overlay" on:click|self={() => dispatch('close')} on:keydown={(e) => { if (e.key === 'Escape') { e.preventDefault(); dispatch('close') } }} role="presentation">
   <div class="modal">
     <header class="preview-header">
       <div class="preview-title">