feat: modern message action icons — larger, distinctive
Icons swapped to more distinctive Lucide variants:
- Copy → ClipboardCopy (clipboard with arrow, instantly recognizable)
- Edit → SquarePen (filled square with pen, modern)
- Regenerate → RotateCcw (single-arrow rotate, cleaner than RefreshCw)
- Delete/Volume stay (already good)
Size: 36dp touch target, 20dp icons (was 32/18). Tint alpha 0.50→0.55
for better visibility. Added ClipboardCopy, SquarePen, RotateCcw, PenLine
to KaizenIcons registry.
b2df7e9330