Fix accessibility issues across SelectedRowPanel, GridHeader, and ColumnTitle components#36

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Copilot wants to merge 3 commits intomainfrom

copilot/fix-9fb40cee-cfa0-4ecc-bc94-3f3fa106a973

Commits on Jul 31, 2025

Initial plan
Copilot
committed
Fix accessibility issues in SelectedRowPanel, GridHeader, and ColumnTitle components

Copilot
and
skylar-anderson
committed
Complete accessibility improvements - add ResizeObserver mock for testing

Copilot
and
skylar-anderson
committed