feat(02-01): add CSS for add-set button, delete-set button, and set-type modal
- .add-set-btn: full-width dashed border button, 44px touch target, accent hover
- .delete-set-btn: 36px wide inline button, subtle opacity, red on hover, disabled state
- .set-type-modal-overlay: fixed fullscreen overlay with semi-transparent dark background
- .set-type-modal: bottom-sheet card (border-radius top only), max-width 600px
- .set-type-option: full-width option card with label/description layout, 56px tall
- .set-type-option.dropset: accent-colored title for dropset option
- .set-type-cancel: borderless cancel button, 44px touch target
- Uses existing dark theme variables: --bg-card, --bg-secondary, --border, --accent, --text-primary, --text-secondary
clawd
3d8a29cb21