Various UX improvements.

internal/game/battle.go

@@ -736,7 +736,9 @@ func (g *Game) runBattle() (*BattleResult, *PendingBattleDecision) {
 	// not "attacks with" the pet, so no knockout applies. Reports a kill.
 	throwRocks := func(from, target, dice int, source *Card) (killed bool) {
 		tu := sides[target].unit
-		if tu == nil {
+		if tu == nil || dice <= 0 {
+			// No target, or a Per-scaled volley that came out to zero (Royal
+			// Flycatcher / Grizzly with no fainted pets): nothing to animate.
 			return false
 		}
 		roll := 0