feat(角色): 为熊角色添加新的光枪攻击技能

添加新的光枪攻击类型(类型5)，包括：
- 新增光枪子弹预制体及脚本
- 添加光枪音效资源
- 在熊角色中实现光枪攻击逻辑
- 新增光枪轨迹着色器
- 配置攻击冷却时间为5500ms

光枪攻击会发射10-15发彩色追踪子弹，形成环绕效果

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

@@ -0,0 +1,22 @@
+extends BulletBase
+
+@export var allColor: GradientTexture1D = null
+
+@onready var track: Node2D = $"%track"
+@onready var sword: Sprite2D = $"%sword"
+@onready var points: GPUParticles2D = $"%points"
+
+var myColor: Color
+func register():
+	speed = 1
+	damage = 5
+	penerate = 1
+func spawn():
+	myColor = allColor.gradient.sample(randf())
+	track.material = track.material.duplicate()
+	points.process_material = points.process_material.duplicate()
+	setColor(myColor)
+func setColor(color: Color):
+	track.material.set_shader_parameter("color", color)
+	sword.modulate = color
+	points.process_material.color = color

scripts/Contents/Characters/Bear.gd

@@ -11,6 +11,7 @@ func register():
 	attackCooldownMap[2] = 8000
 	attackCooldownMap[3] = 13000
 	attackCooldownMap[4] = 4500
+	attackCooldownMap[5] = 5500
 	sprintMultiplier = 60
 func spawn():
 	texture.play("walk")
@@ -18,6 +19,7 @@ func ai():
 	PresetEntityAI.follow(self, currentFocusedBoss, 200)
 	for i in len(attackCooldownMap.keys()):
 		tryAttack(i)
+	# tryAttack(5)
 func attack(type):
 	var weaponPos = findWeaponAnchor("normal")
 	if type == 0:
@@ -57,6 +59,15 @@ func attack(type):
 				bullet.tracer = currentFocusedBoss
 			await TickTool.millseconds(830.0 / count)
 		return false
+	elif type == 5:
+		var target = currentFocusedBoss.position
+		var count = randi_range(10, 15)
+		for i in range(count):
+			for bullet in BulletBase.generate(preload("res://components/Bullets/BossAttack/Bear/LightGun.tscn"), self, target, 0):
+				bullet.position += Vector2.from_angle(deg_to_rad(360.0 / count * i)) * 1000
+				bullet.rotation = bullet.position.angle_to_point(target)
+			await TickTool.millseconds(1670.0 / count)
+		return false
 	return true
 func sprint():
 	move(Vector2(sign((currentFocusedBoss.position - position).x * sprintMultiplier), 0), true)