The 'showExistingRemove' guard was totalScreenshots >= 2, meaning you
could only delete existing screenshots when at maximum capacity.
Changed to >= 1 so the trash icon appears on every existing screenshot
during edit, regardless of the total count.
The submission wizard required at least one game setting category before
allowing screenshot upload ('Add game settings to enable screenshot upload').
Removed that restriction — screenshots can now be attached to any entry
regardless of whether game settings were configured. The Decky plugin entries
typically don't include structured settings, and they should still support
screenshot attachments.