Description:
When clicking date/time picker fields in the Tag History page, the date range controls shift vertically out of alignment with other toolbar items.

Steps to Reproduce:
1. Navigate to user1/hello-world repository → Tag history tab
2. Click on any date or time picker field in the "Date range:" section
3. Observe controls shift out of alignment

Root Cause:
alignItems="center" on ToolbarItem (TagHistoryToolbar.tsx:42) causes flex layout shift when DatePicker/TimePicker popovers open.

Issue reported via Claude Code