fix: QQ 音乐未登录时搜索给出明确提示（接口对匿名请求返回空结果）

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/src/core/providers/qq/index.ts

@@ -101,6 +101,10 @@ export class QQProvider implements MusicProvider {
       param: { query: keyword, num_per_page: limit, page_num: page, search_type: 0 },
     });
     const list: any[] = data?.body?.song?.list || [];
+    // QQ 音乐搜索接口对未登录请求一律返回空结果
+    if (!list.length && !this.client.auth) {
+      throw Object.assign(new Error('QQ 音乐搜索需要先登录（设置 → 扫码登录）'), { status: 400 });
+    }
     return { items: list.map((t) => this.toSummary(t)), total: data?.meta?.sum ?? list.length, page, limit };
   }
 

web/src/views/SearchView.vue

@@ -110,7 +110,7 @@ const qqHint = computed(() => state.source === 'qq' && qqStatus.value && !qqStat
         </div>
       </form>
       <p v-if="qqHint" class="hint">
-        QQ 音乐尚未登录，只能下载免费曲目。<RouterLink to="/settings">去导入 Cookie →</RouterLink>
+        QQ 音乐尚未登录，搜索与下载都需要登录。<RouterLink to="/settings">去扫码登录 →</RouterLink>
       </p>
     </header>