Filter readdir and linked-case names through /^[a-zA-Z0-9_-]+$/ before
returning them from GET /api/cases. Prevents XSS via maliciously-named
directories reaching frontend inline onclick handlers where escapeHtml
is insufficient (HTML-decoded back to quotes before JS execution).
Also fix misleading "Drag or use arrows" hint (no drag-and-drop exists).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>