feat(pqid): hybrid post-quantum identity, AGPL-3.0 license

Player identity is now Ed25519 and ML-DSA-65 (NIST FIPS 204) together,
both signatures required. An attacker must break lattice assumptions and
elliptic curves, not either one — which covers both the quantum threat to
Ed25519 and the possibility that a 2024 lattice standard does not hold.

Signatures are domain-separated to this application so one captured from
another ML-DSA protocol cannot be replayed.

Licensed AGPL-3.0: a fork stood up as a service must publish its changes,
which is what keeps a provably-fair platform honest.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

go.sum

@@ -1,3 +1,5 @@
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+github.com/cloudflare/circl v1.6.5/go.mod h1:h5LNyxAc5nTue9DS5jT+48en2PSDYt3zdGnz5OstK6c=
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@@ -20,6 +22,8 @@ github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu
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