Adds Genre as a fifth Details field (edit / lock / revert / Yours-Pack
provenance), backed by the existing override store. To make it actually useful,
the genre FILTER and FACET now resolve the per-song override (effective genre =
override else scanned pack genre) — guarded so the common no-override case stays
on the plain indexed column — so a corrected/added genre is immediately
browsable. Genre stays a library-only overlay: it is NOT a write-to-file field
(split WRITE_FIELDS = the four file-safe fields from the five DETAIL_FIELDS), so
Write to file leaves the genre override in place and the copy says so. The
Match→Details bridge also carries a candidate's first genre.
Tests: effective-genre facet + filter, and that a value-less lock doesn't invent
an effective genre.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>