feat(子弹系统): 重构伤害计算并添加音效

将子弹的伤害属性从`damage`重命名为`baseDamage`，并引入`damageMultipliers`数组支持多段伤害
为火山武器添加三段攻击音效并调整伤害倍率
更新相关武器和子弹脚本以适配新的伤害系统

scripts/Contents/Bullets/BossAttack/Bear/ArrowSeven.gd

@@ -13,7 +13,7 @@ var forwarded: bool = false
 
 func register():
 	speed = 1
-	damage = 1
+	baseDamage = 1
 func spawn():
 	myColor = allColor.gradient.sample(randf())
 	superlight.material = superlight.material.duplicate()

scripts/Contents/Bullets/BossAttack/Bear/ForeverRainbow.gd

@@ -5,7 +5,7 @@ extends BulletBase
 var myColor: Color
 
 func register():
-	damage = 1
+	baseDamage = 1
 	penerate = 1
 func spawn():
 	myColor = allColor.gradient.sample(randf())

scripts/Contents/Bullets/BossAttack/Bear/LightGun.gd

@@ -10,7 +10,7 @@ extends BulletBase
 var myColor: Color
 func register():
 	speed = 1
-	damage = 1
+	baseDamage = 1
 	penerate = 1
 func spawn():
 	myColor = allColor.gradient.sample(randf())

scripts/Contents/Bullets/BossAttack/Bear/SunDance.gd

@@ -11,7 +11,7 @@ var myColor: Color
 
 func register():
 	speed = 0
-	damage = 1
+	baseDamage = 1
 	penerate = 1
 func spawn():
 	myColor = allColor.gradient.sample(randf())

scripts/Contents/Bullets/BossAttack/KukeMC/HeavyCrystal.gd

@@ -15,5 +15,5 @@ func ai():
 		track.visible = false
 		hitbox.disabled = false
 		PresetBulletAI.forward(self, rotation)
-		damage = speed / 5
+		baseDamage = speed / 5
 		speed *= 1.15