feat: handle non-letter characters in actor names with separator rows

Display spaces, hyphens and other non-letter characters as static cells
instead of input fields, and add separator rows in the grid for
non-alphabetic characters in the main actor's name.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

assets/react/controllers/ActorPopover.jsx

@@ -8,7 +8,7 @@ export default function ActorPopover({ actorName }) {
         open: isOpen,
         onOpenChange: setIsOpen,
         middleware: [offset(8), flip(), shift()],
-        placement: 'top',
+        placement: 'left',
     });
 
     const click = useClick(context);