fix: Avoid redundant table column measurements on re-render

[TrevorBurnham]

This PR reduces unnecessary DOM measurements when a table with "sticky" features (stickyColumns or stickyHeader) re-renders.

ColumnWidthsProvider runs a useEffect that depends on its visibleColumns array. That effect calls updateColumnWidths(), which synchronizes sticky cells by reading layout from the DOM via getBoundingClientRect() (the sticky branch of getColumnStyles). In InternalTable, the arrays passed to the provider — visibleColumnDefinitions and the derived visibleColumnWidthsWithSelection / visibleColumnIdsWithSelection — are rebuilt as fresh arrays of fresh objects on every render, causing the provider's effect to re-fire. These unnecessary calculations contribute to input lag when users type in a sticky table's searchbox.

This PR memoizes those derivations in InternalTable with useMemo:

• visibleColumnDefinitions — keyed on columnDefinitions, columnDisplay, and visibleColumns.
• visibleColumnWidthsWithSelection / visibleColumnIdsWithSelection — keyed on hasSelection and visibleColumnDefinitions.

Benefits

Measured getBoundingClientRect calls per re-render with unchanged columns:

Configuration	Before	After
stickyColumns	3	0
stickyHeader	5	3

The remaining reads come from StickyHeader's own per-render synchronization, a separate mechanism this PR does not change (a candidate for a follow-up).

Non-sticky tables benefit in a smaller way from reduced array allocations.

How has this been tested?

• Added two unit tests in src/table/__tests__/columns-width.test.tsx:
  • does not measure column widths when re-rendering with unchanged columns — re-renders with new items but identical columnDefinitions and asserts that no getBoundingClientRect calls occur. This test fails on main (measurements still happen) and passes with this change.
  • does measure column widths when the columns change — a negative control that re-renders with an added column and asserts measurement still occurs, confirming the first test isn't trivially passing.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.50%. Comparing base (b03b69b) to head (df5a394).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4609   +/-   ##
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  Coverage   97.50%   97.50%           
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  Files         948      948           
  Lines       30275    30317   +42     
  Branches    11039    11046    +7     
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+ Hits        29520    29562   +42     
  Misses        748      748           
  Partials        7        7           

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