UX improvement: add visual feedback to theme picker TUI

[andrejdaskalov]

As discussed on the discord server, prompted by a news article author struggling to use the TUI, I have realized that many people are unaware of the possibility to press c in the theme picker to copy the theme name (including myself). I believe the biggest issue is that there is no feedback at all when copying a theme name to the clipboard. Therefore, I propose a simple change:

• showing a toast to let the user know it was copied to clipboard (like when you use the right-click menu action)
• and optionally, having a more prominent and permanent hint for actions like these (like at the bottom of the UI for example)

I believe these changes while simple, would greatly improve the UX for the theme picker.

Feel free to let me know your thoughts on this!

[pluiedev]

If by "toast" you mean like a copy-to-clipboard toast, that would sadly be #2353 territory. Definitely welcome to making the UX more responsive, though.

[andrejdaskalov]

We could also do this inside the TUI for now? Any feedback on the action would be an improvement.