fix(BulletBase): 将碰撞检测从body_entered改为area_entered

修复子弹碰撞检测逻辑，使用area_entered代替body_entered以正确检测碰撞区域
同时调整Volcano子弹的切割速度为0.7以改善游戏体验

scripts/Contents/Bullets/Volcano.gd

@@ -10,7 +10,7 @@ var dmg5: float = 0
 var splitAngle: float = 10
 
 func register():
-	setupCuttable(0.1)
+	setupCuttable(0.7)
 func ai():
 	animator.speed_scale = launcher.fields.get(FieldStore.Entity.ATTACK_SPEED) * speedScale
 	PresetBulletAI.lockLauncher(self, launcher, true)

scripts/Statemachine/BulletBase.gd

@@ -88,13 +88,13 @@ func _physics_process(_delta: float) -> void:
 		tryDestroy()
 
 func setupCuttable(cutSpeed: float):
-	body_entered.connect(
+	area_entered.connect(
 		func(body):
 			var entity = EntityTool.fromHurtbox(body)
 			if entity:
 				speedScale = cutSpeed
 	)
-	body_exited.connect(
+	area_exited.connect(
 		func(body):
 			var entity = EntityTool.fromHurtbox(body)
 			if entity: