Bump every mesh-llm git dependency in buzz-relay and buzz-desktop from
the v0.76.0-rc4 tag to v0.76.0-rc6, and regenerate both lockfiles at
tag commit a8ddb455.
Verification: cargo check -p buzz-relay --all-targets and cargo check
--manifest-path desktop/src-tauri/Cargo.toml --features mesh-llm
--all-targets pass. The desktop check retains the pre-existing
unreachable-code warning in commands/workspace.rs. The buzz-relay package
suite compiled rc6 and ran 892 passing tests, but its existing mesh demo
forwarded-arm test timed out with HTTP 504 twice.
Co-authored-by: Michael Neale <michael.neale@gmail.com>
Signed-off-by: Michael Neale <michael.neale@gmail.com>