update_song_meta coerces a non-numeric/empty year to "" before persisting,
but writeToFile optimistically set song.year to the raw typed text — so the
library card flashed e.g. "abcd" until the next natural refresh. Apply the
same integer coercion client-side so the in-memory song matches what was
written.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>