Replace grep-based restore with SHA1 matching via database.json.
The old grep heuristic failed for assets with renamed basenames
(dsi_nand_batocera42.bin) or special characters (MAME dots vs
spaces), and only restored to the first .gitignore match when
multiple paths shared a basename.
Fix 3 broken data directory sources:
- opentyrian: buildbot URL 404, use release asset
- syobonaction: invalid git_subtree URL, use GitHub archive
- stonesoup: same fix, adds 532 game data files
resolve_platform_cores() links platforms to their cores via
three strategies: all_libretro, explicit list, system ID
fallback. Pack generation always includes core requirements
beyond platform baseline. Case-insensitive dedup prevents
conflicts on Windows/macOS. Data dir strip_components fixes
doubled paths for Dolphin and PPSSPP caches.
