feat(角色): 为熊角色添加阶段转换功能

添加阶段转换系统，当熊的生命值低于50%时进入第二阶段
- 添加mask精灵用于阶段变化视觉效果
- 实现enterStage和exitStage方法处理阶段转换
- 添加stageAnimator处理转换动画
- 调整攻击7的音效播放位置

components/Characters/Bear.tscn

@@ -1,4 +1,4 @@
-[gd_scene load_steps=26 format=3 uid="uid://m60bwhdpbem8"]
+[gd_scene load_steps=30 format=3 uid="uid://m60bwhdpbem8"]
 
 [ext_resource type="PackedScene" uid="uid://cvogxi7mktumf" path="res://components/Abstracts/EntityBase.tscn" id="1_3ves7"]
 [ext_resource type="Script" path="res://scripts/Contents/Characters/Bear.gd" id="2_kh2af"]
@@ -34,6 +34,58 @@ animations = [{
 [sub_resource type="RectangleShape2D" id="RectangleShape2D_akdh6"]
 size = Vector2(335, 344)
 
+[sub_resource type="Animation" id="Animation_sxh2u"]
+length = 0.001
+tracks/0/type = "value"
+tracks/0/imported = false
+tracks/0/enabled = true
+tracks/0/path = NodePath(".:scale")
+tracks/0/interp = 1
+tracks/0/loop_wrap = true
+tracks/0/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 0,
+"values": [Vector2(-1, 1)]
+}
+
+[sub_resource type="Animation" id="Animation_vxanw"]
+resource_name = "left"
+tracks/0/type = "value"
+tracks/0/imported = false
+tracks/0/enabled = true
+tracks/0/path = NodePath(".:scale")
+tracks/0/interp = 1
+tracks/0/loop_wrap = true
+tracks/0/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 0,
+"values": [Vector2(-1, 1)]
+}
+
+[sub_resource type="Animation" id="Animation_nuh11"]
+resource_name = "left"
+tracks/0/type = "value"
+tracks/0/imported = false
+tracks/0/enabled = true
+tracks/0/path = NodePath(".:scale")
+tracks/0/interp = 1
+tracks/0/loop_wrap = true
+tracks/0/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 0,
+"values": [Vector2(1, 1)]
+}
+
+[sub_resource type="AnimationLibrary" id="AnimationLibrary_dwflo"]
+_data = {
+"RESET": SubResource("Animation_sxh2u"),
+"left": SubResource("Animation_vxanw"),
+"right": SubResource("Animation_nuh11")
+}
+
 [sub_resource type="Curve" id="Curve_u430e"]
 _data = [Vector2(0, 0), 0.0, 0.0, 0, 0, Vector2(0.2, 1), 0.0, 0.0, 0, 0, Vector2(1, 0), 0.0, 0.0, 0, 0]
 point_count = 3
@@ -125,6 +177,11 @@ visible = false
 position = Vector2(-2.5, -1)
 shape = SubResource("RectangleShape2D_akdh6")
 
+[node name="animator" parent="texture" index="1"]
+libraries = {
+"": SubResource("AnimationLibrary_dwflo")
+}
+
 [node name="normal" type="Node2D" parent="texture/weapons" index="0"]
 
 [node name="sprintParticle" type="GPUParticles2D" parent="texture" index="6"]
@@ -136,6 +193,8 @@ process_material = SubResource("ParticleProcessMaterial_5v3nj")
 texture = ExtResource("13_v2sdb")
 
 [node name="mask" type="Sprite2D" parent="texture" index="7"]
+unique_name_in_owner = true
+visible = false
 material = SubResource("ShaderMaterial_6h05p")
 texture = ExtResource("13_v2sdb")