refactor: 替换硬编码文本为多语言配置

1. 替换分销等级页标题拼接的硬编码语言文本
2. 替换AI聊天页面的硬编码提示文本为多语言key
3. 新增完整的多语言翻译配置项

pages_promotion/fenxiao/level.vue

@@ -218,7 +218,7 @@
 				}
 			},1000);
 
-			if (this.fenxiaoWords && this.fenxiaoWords.fenxiao_name) this.$langConfig.title(this.fenxiaoWords.fenxiao_name + '{{ $lang('fenxiao.level') }}');
+			if (this.fenxiaoWords && this.fenxiaoWords.fenxiao_name) this.$langConfig.title(this.fenxiaoWords.fenxiao_name + this.$lang('fenxiao.level'));
 
 			if (this.storeToken) {
 				this.getFenxiaoInfo();