feat: B站首页推荐 — 个性化推荐/音乐区排行/热门视频

- BiliBiliProvider.getDailyRecommendSongs: 个性化推荐（登录后更准确），
  fallback 到音乐区排行榜
- BiliBiliProvider.getPopularVideos: 热门视频列表
- 新增 GET /api/music/bilibili/popular 端点
- 首页新增"B站热门"板块，带B站蓝色徽标
- Store 缓存 bilibiliPopular 数据

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/web/api/music.ts

@@ -197,6 +197,23 @@ export function createMusicRouter(
     }
   });
 
+  // B站热门视频
+  router.get("/bilibili/popular", async (req, res) => {
+    try {
+      const provider = bilibiliProvider as any;
+      if (provider.getPopularVideos) {
+        const limit = parseInt(req.query.limit as string) || 20;
+        const songs = await provider.getPopularVideos(limit);
+        res.json({ songs });
+      } else {
+        res.json({ songs: [] });
+      }
+    } catch (err) {
+      logger.error({ err }, "Get bilibili popular failed");
+      res.status(500).json({ error: (err as Error).message });
+    }
+  });
+
   // Get current quality
   router.get("/quality", (_req, res) => {
     res.json({