The barrier's model alpha goes to opaque over 1 s, the dwarf is moved,
and it clears over 1 s; orders to him are refused meanwhile (new
game::FilterCreatureOrders). The art's duration in its definition is a
fixed 4 s (was 7 + level), which the barrier, its bonus and the tooltip use.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>