A single-use, user-designated 'which release does this track belong to' answer.
Written when the user picks a release in the Re-identify modal and the file is
staged; the import flow will read it at the top of matching and consume it.
- rematch_hints table (additive, IF NOT EXISTS + indexes) keyed on staged_path
with content_hash as a rename-proof fallback.
- core/imports/rematch_hints.py: pure DB seam over an injected cursor
(create/find/consume/list) + a cheap size+head+tail file fingerprint.
- exempt_dedup baked into the hint (a re-identify must bypass dedup-skip);
replace_track_id carried for deferred post-success cleanup.
Inert until wired (Phase 5) — nothing calls it yet. 9 seam tests.
