server : (web UI) add copy button for code block, fix api key

[ngxson]

Added Copy button for code blocks:

It also follow the window as user scroll up (position sticky):

This PR also fixes a problem with API key set, as reported via this comment: #10175 (comment)

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[ggerganov]

There is a subtle bug with the scrolling:

• Scroll to the bottom of the generated session (or to the top)
• Using a mouse with scroll wheel, first start scrolling down and then up - nothing happens
• If you first scroll up and the down - it works

Edit: please ignore - everything is OK

[ngxson]

@ggerganov I'm not sure if I understand it correctly, but I suspect that it may have something to do with the "show-on-hover" that I have on the button.

I removed that in the last commit, so the copy button now always show on code snippet (no need to hover). Please let me know if that fixes the issue. Thanks.

[ggerganov]

Ah, apologies for the distraction - this seems to be a browser behaviour that somehow I haven't noticed before. All scrolls on other pages also work like that, so it's not specific to this UI.

[ngxson]

No problem. Anw, I think having the copy button being persistent (and not "on hover") feels more consistent overall, so I'll keep it and merge this PR now. Thanks for testing it!