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
generate_site.py resolves files on disk for gap analysis.
Without large files and data directories, the deployed site
showed 148 missing platform files and 207 unsourced core
complement files.
