Production catalog generation previously prepared every game serially and computed transfer-chunk hashes for extracted .eti files even though those hashes were discarded. Enable Rayon-backed BLAKE3 hashing, process selected games through the shared available-CPU pool, and hash large read blocks with update_rayon. Extracted outputs now use a whole-file-only hash path. Manifest collection remains deterministic and the independent second verification pass is preserved.
Test Plan:
- `just clippy` -- passed
- `just test` -- passed
ddidderr
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