refactor(Statemachine): 重构实体状态栏和Boss栏逻辑

将EntityStateBar的_ready逻辑移到EntityBase中统一管理
修改BossBar的更新逻辑从_physics_process改为_process
调整Wave配置中Boss的出现波次从8改为1

scripts/Statemachine/BossBar.gd

@@ -4,7 +4,9 @@ class_name BossBar
 @onready var nameLabel: Label = $"%name"
 @onready var valueLabel: Label = $"%value"
 
-func _physics_process(_delta):
+func _ready():
 	if is_instance_valid(entity):
 		nameLabel.text = entity.displayName
+func _process(_delta):
+	if is_instance_valid(entity):
 		valueLabel.text = "%.2f" % (entity.health / entity.fields[FieldStore.Entity.MAX_HEALTH] * 100)