Qt Bridge: Provide visual confirmation that the export has completed

When exporting, the last thing that shows on the Figma plugin is "Packing archive...". After the user confirms the *.qtbridge filename and clicks "Save", the Save-As dialog disappears but "Packing archive..." remains on screen. Nothing else is shown.

This can leave the user feeling uncertain about whether the packing is still in progress or not. Is the packing operation frozen?

Suggestion

After the export is completed, print a message to confirm this (e.g. "Archive exported to C:\path\to\testing.qtbridge")