Move the ~63-LOC `seek` action body into `runSeek(set, get, progress)`
in `src/store/seekAction.ts`, following the helper-with-thin-wrapper
pattern from E.37 (updateReplayGain).
The action handles the full seek path: 0..1 fraction → bounded time,
100 ms debounce, hot-cache-rebind branch via playTrack, and the
recoverable-seek-error retry burst (visual target pin + restart on
"not seekable" + bounded retry window).
Pure code-move. playerStore.ts: 938 → 868 LOC (−70).
Frank Stellmacher