Contract 11.7.1

Two reads that were slower than they should be.

• elixir_timeline: the skip_empty check reads quiet_crossed from each subject's own battles instead of scanning every battle, so a poll whose kinds include quiet_crossed costs milliseconds rather than half a second. What it decides is unchanged.
• elixir_data_insights: the snapshot counts come from one read of the snapshots instead of four. The numbers are unchanged.

No schema change. JSON API 3.1.0 is unchanged.