ed25519 over checksums.txt: llmgw release keygen makes the pair, CI signs
with the RELEASE_SIGNING_KEY secret when it is set, and release.Install
refuses an unsigned or wrongly signed release when the build embeds a
trusted key (internal/release/trusted.pub, empty for now) or
LLMGW_RELEASE_KEY names one.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
