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/Contents/Bullets/BigLaser.gd

@@ -2,6 +2,7 @@ extends BulletBase
 class_name BigLaser
 
 var dotTime: float = 100
+var executeAtk: float = 0.25
 
 func spawn():
 	CameraManager.shake(5000, 100) # 激光会运行5秒（5000毫秒），期间震屏超高强度
@@ -17,3 +18,10 @@ func applyDot():
 	await TickTool.millseconds(dotTime / launcher.fields[FieldStore.Entity.ATTACK_SPEED])
 	await TickTool.frame() # 等至少一帧，防止跳帧导致没检测到伤害
 	return true
+func damageOverride(origin: float, something: Variant):
+	if something is EntityBase:
+		return origin * (1 + (executeAtk if something.getHealthPercent() < 0.3 else 0.0))
+	elif something is ObstacleBase:
+		return origin * (1 + (executeAtk if something.getHealthPercent() < 0.3 else 0.0))
+	else:
+		return origin