* fix(ui): center skills empty state and fix terminal toolbar overlap
Fix two UI layout issues in the settings and terminal views.
Skills empty state:
- Add h-full to the max-w-3xl content wrapper so flex centering works
- Make book icon responsive (h-10 w-10 sm:h-12 sm:w-12)
- Add px-4 padding for narrow viewports
Terminal toolbar:
- Reserve right padding (pr-20) for dock fullscreen/close buttons
- Remove pb-1 from quick keys to fix vertical misalignment
- Change shrink-0 to min-w-0 for graceful shrinking on narrow widths
* ref(ui): gate pr-20 padding on desktop runtime only