feat: improve focus behavior on terms, anchors, clipboard button

[martyanovandrey]

terms

• you can focus on terms via tab and open via enter
• when a term is open it locks the focus, you can only switch between elements inside the term while it is open

code block

• wrapped our svg “button" for copying the code in a real
• now you can focus on it, it becomes visible along with the focus
• I change display: none -> opacity: 0 like anchors

anchors

• make them visible not only on hover, but also on focus