Previously, hotspots were sorted by raw hot values directly, but different
platforms use vastly different scales (Toutiao ~10M, Weibo ~1M, Baidu ~100K),
causing Toutiao to dominate all results while Weibo and Baidu entries were
always truncated.
Now uses rank-based normalization (0-100) within each source before merging,
so cross-platform sorting gives equal weight to each platform's top stories.
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>