fix: respect cursorlineopt in the diff and the list surfaces

[undont]

Summary

• the diff's cursor-line overlay painted over the text whenever cursorline was on, even with cursorlineopt=number. it now paints only when cursorlineopt includes line, screenline or both; screenline still tints the whole line, since an extmark can't target one screen row
• the OptionSet repaint also fires on cursorlineopt, so changing it mid-session updates the overlay straight away
• the panel, history and pr checks lists set cursorlineopt=line locally, so a global number-only setting no longer hides their selected row

Test plan

• make check clean