feat(武器系统): 为BigLaser武器添加执行伤害和升华选项

- 在ObstacleBase和EntityBase中添加getHealthPercent方法用于获取生命值百分比
- 修改bulletHit方法支持伤害覆盖参数
- 为BigLaser武器添加5个升华选项，包括临界斩杀效果
- 实现damageOverride方法根据目标生命值动态调整伤害
- 修复store数值可能为负数的问题

scripts/Statemachine/EntityBase.gd

@@ -282,10 +282,10 @@ func takeDamage(baseDamage: float, crit: bool = false, perfectMiss: bool = false
 	if health <= 0:
 		tryDie(null)
 	return resultDamage
-func bulletHit(bullet: BulletBase, crit: bool):
+func bulletHit(bullet: BulletBase, crit: bool, damageOverride = "none"):
 	# 当受伤时
 	hurtAnimator.play("hurt")
-	var damage = bullet.calculateDamage(crit)
+	var damage = bullet.calculateDamage(crit) if damageOverride == "none" else damageOverride
 	var perfectMiss = false
 	if sprinting:
 		playSound("miss")