* refactor(tabs): delete unused copy-tab and merge-group store actions
copyUnifiedTabToGroup and mergeGroupIntoSibling had no callers outside
the store and its tests. Tests that used the copy action as a setup step
now create the duplicate tab directly, the same call the action made.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
* chore(tabs): follow the split-ratio file rename in the layout-writer baseline
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>