feat(武器): 添加彩虹猫之刃武器及相关资源

添加彩虹猫之刃武器，包含以下内容：
- 新增彩虹猫子弹和武器贴图资源
- 实现彩虹猫子弹和武器逻辑脚本
- 添加武器预制体和相关动画效果
- 在公鸡角色中默认装备该武器
- 修改子弹基类添加AI调用逻辑

scripts/Contents/Bullets/Meowmere.gd

@@ -0,0 +1,4 @@
+extends BulletBase
+
+func ai():
+	PresetBulletAI.lockLauncher(self, launcher, true)

scripts/Contents/Bullets/RainbowCat.gd

@@ -0,0 +1,5 @@
+extends BulletBase
+class_name RainbowCat
+
+func ai():
+	PresetBulletAI.forward(self, rotation)

scripts/Contents/Weapons/Meowmere.gd

@@ -0,0 +1,13 @@
+@tool
+extends Weapon
+
+func update(to, origin, _entity):
+	origin["atk"] += 7 * to * soulLevel
+	origin["count"] = 1 * soulLevel
+	return origin
+func attack(entity: EntityBase):
+	var weaponPos = entity.findWeaponAnchor("normal")
+	for i in BulletBase.generate(preload("res://components/Bullets/Meowmere.tscn"), entity, weaponPos, weaponPos.angle_to_point(get_global_mouse_position())):
+		i.damage = readStore("atk")
+	for i in readStore("count"):
+		BulletBase.generate(preload("res://components/Bullets/RainbowCat.tscn"), entity, weaponPos, weaponPos.angle_to_point(get_global_mouse_position()))