Fix one-time consent for external media

[SoftCreatR]

The Fancybox consent plugin only handles permanently enabling external media. Clicking “Display content once” still invokes the generic user-consent handler, which expects a target or payload and can attempt to insert content relative to an already detached consent element.

This results in an empty Fancybox slide and the following error:

The reference element has no parent, but the insert position was set to 'before'.

This PR handles one-time consent directly in the Fancybox plugin:

• Restores the original media type for the current slide.
• Refreshes the current slide so the external media is loaded.
• Prevents the generic payload-based consent handler from processing the Fancybox button.
• Leaves permanent consent behavior unchanged.