fix: save question reorder on drop instead of during drag

[pringelmann]

Summary

Drag-and-drop reordering saved the wrong order to the backend, so reloading reverted to the old order. Two related causes:

1. Questions and options saved on the draggable's change event, which fires repeatedly during the drag (before the new order is committed) instead of once on release. Switched to update, which fires once on drop.
2. Options needed an extra fix: saveOptionsOrder reads the order from the options prop, which only updates after the reordered array round-trips through the parent. Saving synchronously on drop still read the stale order. The drag now sets the existing dirtyOptionsType flag so the debounced watcher saves once the new order has settled, the same path the move up/down buttons already use.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)