Support themes / skin customization for the app UI

It would be great if Paste could support UI skin/theme customization.

Requested options:

• Light / Dark / Auto mode
• Multiple accent colors or predefined skins
• Optional custom background/transparency for the Paste panel
• Per-device theme sync via iCloud

Why this matters:

• Better readability in different environments
• Better personal preference fit for long daily usage
• More visual consistency with user desktop setup

Thank you!