2782

Added

• Serial-based ROM lookup — ROMMetadataProvider gains searchROM(bySerial:systemID:) protocol method with a default no-op implementation for backward compatibility; OpenVGDB implements it via ROMs.romSerial, LibretroDB via games.serial_id.
• PVLookup serial aggregation — PVLookup.searchROM(bySerial:systemID:) queries OpenVGDB and LibretroDB in parallel, merges results, and caches answers in a dedicated 256-entry LRU cache.

Changed

• MatchType — Added case bySerial(String) so the import pipeline can record when a ROM was matched by disc serial.