Enemies no longer attack; add a fixed bullet-ring emitter and make lasers permanent obstacles

walker.gd lost its firing code entirely: monsters now only patrol and hurt on contact, so the only way past is footwork or the key throw + W warp. New bullet_ring prefab fires a set number of bullets evenly spread over a fixed arc on a timer, with directions derived only from its own exports, so every volley is identical and the pattern can be memorised; the level places one at cell (12,12) aimed upward with the 12 bullets spread over 180 degrees. laser.gd gained always_on, defaulting to true, so the five copied lasers are now static hazards that are always lit and damage anything overlapping them rather than blinking on and off. Bullets now stop when they spawn inside terrain.

scripts/walker.gd

@@ -1,11 +1,8 @@
 extends CharacterBody2D
 
-## 小怪：在平台上左右巡逻，并且按固定节奏发射弹幕。
-## **打不死** —— 从上方踩上去也一样会被扣血。
-## 弹道方向是写死的（不追着玩家走），所以每一波的弹道完全一样，
-## 玩家可以背下空隙走位躲过去，或者用「扔钥匙 + W 传送」直接穿过去。
-
-const BULLET := preload("res://scenes/prefabs/enemies/bullet.tscn")
+## 小怪：只在平台上左右巡逻，**不发射任何东西**，也**打不死**。
+## 作用纯粹是挡路 + 碰到扣血，逼玩家走位。
+## 弹幕交给专门的「弹幕源」节点负责。
 
 @export_category("巡逻")
 @export var speed: float = 28.0
@@ -13,31 +10,12 @@ const BULLET := preload("res://scenes/prefabs/enemies/bullet.tscn")
 @export var start_direction: int = -1
 ## 掉头后的冷却时间：防止贴着墙时每帧都掉头、结果原地抖动
 @export var turn_cooldown: float = 0.25
-## 接触玩家扣几颗心
+## 速度设成 0 就变成待在原地不动的障碍
 @export var damage: int = 1
-## 速度设成 0 就变成固定炮台（弹幕就完全静止可背板了）
-
-@export_category("弹幕")
-@export var fires_bullets: bool = true
-## 发射间隔（秒）
-@export var fire_interval: float = 2.0
-## 开场后第一次发射前的延迟
-@export var fire_delay: float = 1.0
-## 每次发射几颗
-@export var bullet_count: int = 3
-## 扇面张开角度
-@export var spread_deg: float = 60.0
-## 扇面中心朝向（度）：0=右 90=下 180=左 270=上
-@export var base_angle_deg: float = 0.0
-## 开火方向跟随巡逻朝向（打开时 base_angle_deg 只当上下偏移用）
-@export var aim_along_facing: bool = true
-@export var bullet_speed: float = 70.0
-@export var bullet_color: Color = Color(1.0, 0.35, 0.7)
 
 var direction: int = -1
 
 var _turn_timer: float = 0.0
-var _fire_timer: float = 1.0
 
 @onready var sprite: Sprite2D = $Sprite
 @onready var floor_probe: RayCast2D = $FloorProbe
@@ -48,7 +26,6 @@ func _ready() -> void:
 	add_to_group("enemy")
 	direction = -1 if start_direction < 0 else 1
 	_apply_direction()
-	_fire_timer = fire_delay
 	touch_area.body_entered.connect(_on_touch)
 
 
@@ -69,33 +46,6 @@ func _physics_process(delta: float) -> void:
 
 	move_and_slide()
 
-	if fires_bullets:
-		_fire_timer -= delta
-		if _fire_timer <= 0.0:
-			_fire_timer = maxf(fire_interval, 0.05)
-			fire()
-
-
-## 按固定扇面发射一批子弹。方向是算死的，不参考玩家位置，
-## 所以每一波的弹道都一样，玩家能背下来找空隙。
-func fire() -> void:
-	var n: int = maxi(bullet_count, 1)
-	var base_deg: float = base_angle_deg
-	if aim_along_facing:
-		base_deg = 0.0 if direction > 0 else 180.0
-	var base := deg_to_rad(base_deg)
-	var spread := deg_to_rad(spread_deg)
-	for i in n:
-		var t: float = 0.0 if n == 1 else (float(i) / float(n - 1) - 0.5)
-		var ang := base + spread * t
-		var bullet := BULLET.instantiate()
-		# 这两个属性必须在 add_child 之前设好，子弹的 _ready 会拿它们生成贴图
-		bullet.bullet_color = bullet_color
-		bullet.speed = bullet_speed
-		get_parent().add_child(bullet)
-		bullet.global_position = global_position + Vector2(0.0, -2.0)
-		bullet.launch(Vector2(cos(ang), sin(ang)), bullet_speed)
-
 
 func _apply_direction() -> void:
 	if sprite != null: