Various bug fixes and improvements.

internal/game/game.go

@@ -159,6 +159,15 @@ func (g *Game) battleDraw(n int) int {
 // rollRockDie rolls one rock die: 0, 1, or 2 with equal probability.
 func (g *Game) rollRockDie() int { return g.battleDraw(3) }
 
+// battleShuffle does an in-place Fisher-Yates over a battle deck, routing its
+// randomness through battleDraw like every other in-battle draw (Komodo).
+func (g *Game) battleShuffle(s []Card) {
+	for i := len(s) - 1; i > 0; i-- {
+		j := g.battleDraw(i + 1)
+		s[i], s[j] = s[j], s[i]
+	}
+}
+
 var (
 	ErrNotYourTurn   = errors.New("not your turn")
 	ErrWrongPhase    = errors.New("action not allowed in this phase")