In the dashboard Recent Syncs detail modal, the '→ Wishlist' status on unmatched
tracks is now a button. Clicking it re-adds that exact track to the wishlist with
the SAME context the sync used (source_type='playlist' + the playlist's name/id +
failure_reason), so it's indistinguishable from the original auto-add.
- reconstruct_sync_track_data() (pure, tested): prefers the full cached track from
tracks_json (by source_track_id, then index) so album art/full data carry over;
falls back to the track_result fields; refuses non-'wishlist' rows and rows with
no id (can't re-wishlist a matched/unidentifiable track).
- POST /api/sync/history/<id>/track/<i>/wishlist resolves the entry server-side and
calls the wishlist service; idempotent (reports added vs already-on-wishlist).
- button shows a busy state then '✓ Re-added' / '✓ On wishlist'.
7 pure tests (full-track preference, id-vs-index match, fallback rebuild, non-
wishlist + out-of-range refusal). JS/PY/ruff clean.
