Keyboard-a11y polish to match the codebase's standard
`focus-visible:ring-[3px] focus-visible:ring-ring/40` treatment:
- ToggleSwitch (role=switch, used across every settings/config surface) had
no focus-visible ring — keyboard users got no focus indicator.
- Sheet's close button used a bare `focus:outline-none`; now mirrors the
Dialog close button's ring.
Slider, Button, Input, Select, Tabs, Checkbox, Switch already carry the ring.
DrSmoothl
6d4e8538ea