ci: make required checks dispatchable

[jrandolf]

Summary

• allow manual dispatch of the CI workflow that provides test and proto-check
• allow manual dispatch of the hk workflow that provides Check

This lets maintainers prove all protected checks on main even when a bot-authored merge suppresses push-triggered workflows.

Verification

• mise exec -- hk check --all --slow
• mise exec -- cargo test --workspace
• mise exec -- cargo build --target wasm32-wasip1
• mise exec -- cargo package --locked --allow-dirty