fix: 修复歌曲播放URL处理逻辑并添加元数据获取错误提示

修复播放URL处理逻辑，统一从getPlayableUrl方法获取可播放URL
添加歌曲元数据获取失败时的错误提示
确保songId字段在mapTunehubResult中始终有默认值

frontend/src/App.vue

@@ -167,6 +167,7 @@ import { getPlayUrl, getSongsMeta, createSyncSongFromUrlJob } from "./api";
 import { startTaskListener } from "./components/TaskNotification";
 import storage from "./utils/storage";
 import { getProperPlayUrl } from "./utils/audio";
+import { ElMessage } from "element-plus";
 
 export default {
   data: () => {
@@ -226,6 +227,15 @@ export default {
       let info = metaInfo;
       if (!info) {
         const ret = await getSongsMeta({ url: pageUrl });
+        if (!ret || !ret.data || !ret.data.songMeta) {
+          console.warn("获取歌曲元数据失败", ret);
+          ElMessage({
+            message: "获取歌曲元数据失败，无法播放",
+            type: "warning",
+            duration: 1500,
+          });
+          return false;
+        }
         info = ret.data.songMeta;
         console.log(ret);
       }