- md3-buttons.ts: upgrade ring-2/50 to ring-3 on all three constants (FILLED, OUTLINED, TEXT)
- BackendCard: add focus-visible:outline-none focus-visible:ring-3 focus-visible:ring-primary
- StepIndicator: upgrade group-focus-visible completed-step circle from ring-2/50 to ring-3
- ThemeToggle: add focus-visible ring-3 with ring-inset to both selected/unselected branches
- FieldRenderer: select uses focus-visible:ring-2 (was focus:ring-2); tooltip buttons get focus-visible:ring-2 rounded