[BUGFIX] Table: restore data transform memoization

[kevin-fischer]

Description

Restores the useMemo wrapper around transformData() that was accidentally removed in #415, fixing an infinite re-render loop that breaks sorting and filtering when table transforms are enabled.

Problem: When using table transforms (e.g., merge series) with sorting or filtering, the table becomes unresponsive due to infinite re-renders.

Root cause: Without memoization, transformData() executes on every render, creating a new data reference each time. This triggers React to re-render, which transforms again, creating an infinite loop.

Solution: Restore the useMemo wrapper with dependencies [rawData, spec.transforms] to ensure data is only recalculated when source data or transform configuration changes.

Fixes regression from #415

Screenshots

Before fix - Sorting broken with transforms

before-sorting-bug.mp4

After fix - Sorting works correctly

after-sorting-fixed.mp4

Checklist

• Pull request has a descriptive title and context useful to a reviewer.
• Pull request title follows the [<catalog_entry>] <commit message> naming convention using one of the following catalog_entry values: FEATURE, ENHANCEMENT, BUGFIX, BREAKINGCHANGE, DOC, IGNORE.
• All commits have DCO signoffs.

UI Changes

• Changes that impact the UI include screenshots and/or screencasts of the relevant changes.
• Code follows the UI guidelines.