The ~150-LOC `applyQueueHistorySnapshot` helper that lived inside the
playerStore `create((set, get) => { … })` closure moves out into
`src/store/applyQueueHistorySnapshot.ts`. The function now takes the
zustand `set` / `get` references as explicit parameters; the two
caller sites (`undoLastQueueEdit`, `redoLastQueueEdit`) pass them
through unchanged.
Side-cleanup: four imports that only fed the moved helper drop from
playerStore (getPlaybackSourceKind, queueUndoRestoreAudioEngine,
setPendingQueueListScrollTop, shallowCloneQueueTracks).
playerStore 1706 → 1550 LOC (−156).
The undo/redo flow keeps behaving 1:1 — the function is exported and
deterministic; the closure capture only existed for the set/get pair
which is trivial to pass through.
Frank Stellmacher