refactor: 将代码中的card_lv统一替换为rarity

本次提交完成了全项目范围内术语的统一替换，将原本指代卡牌品质/等级的card_lv字段全部重命名为rarity，对齐了设计文档中的命名规范，避免了术语混淆：
1.  更新了所有配置文件、组件类、数据结构中的字段定义
2.  同步修改了注释、文档说明中的相关表述
3.  修正了英雄、技能、装备卡牌的品质显示逻辑
4.  调整了背景颜色切换、属性计算等相关业务逻辑

assets/script/game/hero/Hero.ts

@@ -74,7 +74,7 @@ export class Hero extends ecs.Entity {
      * 2) 初始化表现与属性数据
      * 3) 播放下落入场并在落地后启用碰撞与移动
      */
-    load(pos: Vec3 = Vec3.ZERO, scale: number = 1, uuid: number = 1001, dropToY: number = pos.y, hero_lv: number = 1, card_lv: number = 1, posIndex: number = -1) {
+    load(pos: Vec3 = Vec3.ZERO, scale: number = 1, uuid: number = 1001, dropToY: number = pos.y, hero_lv: number = 1, rarity: number = 1, posIndex: number = -1) {
         // 英雄始终朝右，表现缩放固定为正向
         scale = 1
         // 英雄等级上限以配置为准，合成可升到 HERO_MAX_LV
@@ -117,8 +117,8 @@ export class Hero extends ecs.Entity {
         model.hero_uuid = uuid;
         model.hero_name = hero.name;
         model.lv = hero_lv;
-        model.card_lv = card_lv;
-        model.base_card_lv = hero.card_lv ?? 1;
+        model.rarity = rarity;
+        model.base_rarity = hero.rarity ?? 1;
         model.type = hero.type;
         model.grow_type = hero.grow_type;
         model.role = hero.role;
@@ -144,7 +144,7 @@ export class Hero extends ecs.Entity {
 
         // 基础属性：固定基础值 × 品质系数（相邻品质差 5%），成长由 grow_type 线性递增提供
         // TODO: 局外升级机制落地后，此处基础值将与存档强化累加重算
-        const qualityCoef = getHeroQualityCoef(hero.card_lv ?? 1);
+        const qualityCoef = getHeroQualityCoef(hero.rarity ?? 1);
         let base_ap = Math.round(hero.ap * qualityCoef);
         let base_hp = Math.round(hero.hp * qualityCoef);
         let base_def = Math.round(hero.def * qualityCoef);