scph3000.bin v2.1J and scph3500.bin v2.2J already existed under
different primary names (scph3500.bin and scph5000.bin respectively).
Add .variants/ entries so by_name resolves both filenames.
verify_single_emulator now calls _find_best_variant on hash mismatch,
matching the platform-level verification path.
Add 3 rare BIOS variants from TOSEC/archive.org:
- Mega CD v1.00s JP (a3ddcc8483) from Myrient TOSEC
- Sega CD Model 2 v2.00 US (310a9081d2) from Myrient TOSEC
- ps1_rom.bin 4MB PS3-extracted (fbb5f59ec3) from archive.org
EmuDeck: 163/164 (99.4%), 1 unknown hash remains (476d68a9)
All other platforms: 0 missing