Adds the libretro thumbnail repository as a first-class artwork source so
region-correct box art (PAL/Europe, Japan, etc.) can be matched directly
to ROM filenames, addressing rommapp/romm#3239.
Implementation follows the SGDB handler pattern (artwork-only, no game
metadata): MetadataSource enum entry, scan-time fetch wired into the
SCAN_ARTWORK_PRIORITY loop, /search/roms integration, MatchRom dialog
chip + cover selection, and a heartbeat flag.
Matching is exact case-insensitive against the directory listing first
(so a ROM named "(Europe)" lands on the (Europe) artwork), with a
JaroWinkler fuzzy fallback at 0.8 that strips parenthetical tags from
both sides. Listings are cached in Redis with a 24h TTL.
`libretro_id` is persisted on the Rom model as the SHA1 hex of the
matched libretro filename — stable across scans, distinct per region,
indexed for lookup. Migration 0077 adds the column.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
