Add a focused runtime integration test file that exercises worker boot state,
lane event emission, hook config merging and execution, task packet roundtrips,
and config validation through the public runtime APIs.
Constraint: Keep the change scoped to integration coverage without touching runtime behavior
Rejected: Reusing broader untracked workspace changes | would mix unrelated work into this request
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: Keep these tests aligned with the public runtime re-exports and cross-module wiring paths
Tested: cargo test -p runtime --test runtime_workflows; cargo test --workspace
Not-tested: No additional lint-only pass beyond rustfmt
Yeachan-Heo