Cardano Updates

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.

Previously hardcoded to Mainnet only, which broke when preview gained a
checkpoints file. Using NonFatal mirrors the existing pattern for
genesis-conway.json: include if present, silently skip if absent.

(cherry picked from commit a6a9ff2a2b6a494a415d72fcb6601d55d8ab4bce)

The echo line used Unicode typographic quotes around the installer path,
causing drt sign to fail to parse the 'Final installer:' line. Drop the
quotes entirely and update the Rust parser to strip only the prefix.

Also replace other curly quotes and ellipsis in the signing echo with
ASCII equivalents while here.

(cherry picked from commit 1beb91b8146146c0a76b2300534383b4cc818a7a)

Bumps the actions group with 1 update: [slackapi/slack-github-action](https://github.com/slackapi/slack-github-action).


Updates `slackapi/slack-github-action` from 3.0.1 to 3.0.2
- [Release notes](https://github.com/slackapi/slack-github-action/releases)
- [Changelog](https://github.com/slackapi/slack-github-action/blob/main/CHANGELOG.md)
- [Commits](https://github.com/slackapi/slack-github-action/compare/v3.0.1...v3.0.2)

---
updated-dependencies:
- dependency-name: slackapi/slack-github-action
  dependency-version: 3.0.2
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
...

Signed-off-by: dependabot[bot] <[email protected]>