[BUG] baseline_low_date shown in place of baseline_high_date

**Describe the bug**
On a widely available feature's overview page, the Baseline status says something like "Widely available since YYYY-MM-DD", however the date shown corresponds to when the feature became _Newly available_, not Widely. As a result, it seems that the feature became Widely available 30 months earlier than it actually did.

**To Reproduce**
Steps to reproduce the behavior:

1. Go to https://webstatus.dev/features/has
2. See the "Widely available" date

**Expected behavior**
The expected date for when the `:has` feature became Widely available is 2026-06-19

**Screenshots**

Start at the :has feature overview at https://webstatus.dev/features/has and trace where the Baseline status gets its Newly available and Widely available dates. Check that the widely available value uses baseline_high_date rather than baseline_low_date; done when the page shows 2026-06-19.

Written by the indexing model from the issue text.