Do not show the library sync popup when the only differences are global x/y changes on library components. We now generate the actual sync changes and only notify if there are real redo-changes to apply.
Run cll/generate-sync-file-changes for candidate libraries and filter out those with empty :redo-changes. The expensive check is deferred via rx/timer 0 so it runs asynchronously and does not block the UI.
Why: Position-only changes are normalized during sync (via reposition-shape) and never propagate to copies; showing the popup in that case was a false positive.
Performance: The check is deferred to the next tick to avoid UI stutter on large files with many libraries.
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