Cardano Updates

Bot api test suite

Bump slackapi/slack-github-action from 3.0.1 to 3.0.2 in the actions group

_convertSnapshot was added to startBootstrap after these tests were
written. Without a mock it falls through to _runCommand → buildMithrilEnv
which fetches genesis/ancillary keys from raw.githubusercontent.com,
causing EAI_AGAIN failures in network-isolated environments.

\${WIN_SIGN_HOST: -HSM} with a space causes bash to parse -HSM as a
substring-from-end offset, treating HSM as a variable. With set -u this
throws "HSM: unbound variable". The correct syntax for a default-value
substitution is \${WIN_SIGN_HOST:-HSM} (no space).

(cherry picked from commit 6a0b73f94349630e3bf0da3a3b60894eb00d95fc)

\${WIN_SIGN_HOST: -HSM} with a space causes bash to parse -HSM as a
substring-from-end offset, treating HSM as a variable. With set -u this
throws "HSM: unbound variable". The correct syntax for a default-value
substitution is \${WIN_SIGN_HOST:-HSM} (no space).

Points mithril input at sl/fix-mismatch-rust-versions branch which
ensures all craneLib instances use the rust-overlay toolchain (1.94)
rather than falling back to nixpkgs rustc (1.91), fixing Darwin builds
that fail with [email protected] requiring rustc 1.93+.

craneLibMusl and craneLibWindows were explicitly overriding to
rust-bin.stable.latest.default, but craneLib (the native path used on
Darwin and aarch64-linux where pkgsMusl is null) was left bare, causing
crane to fall back to nixpkgs' rustc instead of the rust-overlay one.

This caused Darwin builds to fail with rustc 1.91.1 when a transitive
dependency ([email protected]) requires rustc 1.93+.

Extract rustToolchain as a shared binding and apply overrideToolchain to
all three craneLib instances for consistency.