接入编号讲解后端查询

- 使用真实讲解编号解析接口替换本地演示映射
- 成功后复用现有详情页并自动播放讲解
- 增加查询状态、业务错误提示和相关测试

Made-with: Proma

src/usecases/explainUseCase.ts

@@ -78,6 +78,11 @@ export interface ExplainHallSummary {
   guideStopCount: number
 }
 
+export interface ExplainCodeResolution {
+  code: string
+  stopId: string
+}
+
 export class ExplainUseCase {
   constructor(
     private readonly explain: ExplainRepository = explainRepository,
@@ -273,6 +278,15 @@ export class ExplainUseCase {
     })
   }
 
+  async resolveExplainCode(code: string, lang: AudioLanguage = dataSourceConfig.audioLanguage as AudioLanguage): Promise<ExplainCodeResolution> {
+    const stopInfo = await this.audioPlayInfo.getStopInfoByCode(code, lang)
+    const stopId = stopInfo.resolvedStopId || stopInfo.playTargetId || stopInfo.targetId
+    if (!stopInfo.available || !stopId) {
+      throw new Error('该编号的讲解内容暂不可用')
+    }
+    return { code: code.trim(), stopId }
+  }
+
   async enterExplainDetail(request: ExplainDetailEntryRequest) {
     const stopId = this.resolveDetailStopId(request)
     if (!stopId) throw new Error('讲解点 ID 不能为空')