Harden 0.4.0 migration: Node 22 CI + Sui client script compatibility

[arbuthnot-eth]

Summary

The recent @mysten/messaging 0.4.0 migration to latest Sui/Seal still has merge-risk in two places:

1. Runtime mismatch in CI/publish workflows:
   • workflows run on Node 20
   • @mysten/sui@2.4.0 requires Node >=22
2. Script API typing drift:
   • scripts/utils.ts still referenced older client typing/method style
   • this caused TS compile failures in scripts package

Impact

• CI can pass/fail unpredictably depending on runtime assumptions.
• Publish jobs may break once dependency constraints are enforced.
• Local helper scripts are incompatible with the current Sui client typing/API surface.

Proposed Fix

• Update GitHub workflows to Node 22.
• Add integration coverage in CI for localnet path.
• Keep publish gate strict by running unit tests pre-publish.
• Align scripts/utils.ts with current @mysten/sui client API/typing.
• Declare node >=22 in packages/messaging engines to match dependency requirements.

Validation

• pnpm -C packages/messaging build
• pnpm -C packages/messaging lint
• pnpm -C packages/messaging test:unit
• pnpm -C scripts exec tsc -p tsconfig.json --noEmit

(Integration tests require Docker/testcontainers runtime in CI or a Docker-enabled local environment.)