feat(tables): virtualize data grid with bounded copy and chunked delete (#4693)

* feat(tables): virtualize data grid with bounded copy and chunked delete

* fix(tables): keyboard scroll past sticky header, copy toast row count, clipboard error handling

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix(tables): keep copy/cut progress toast until the operation completes

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix(tables): stop bulk cut chunks on first failure, reconcile grid on error

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: TheodoreSpeaks