## What changed?
Adds a top-level `nexusworkflowref` package exposing two functions that
convert a Nexus operation completion token between its HSM and CHASM
forms:
- `HSMRefToCHASMRef` — HSM `StateMachineRef` token → CHASM
`ChasmComponentRef` token
- `CHASMRefToHSMRef` — the reverse
Both directions rebuild the target framework's ref from the fields
shared by the two representations (namespace, workflow, run, scheduled
event ID, request ID). `CHASMRefToHSMRef` only accepts workflow-backed
operations: it verifies the ref's `WorkflowArchetypeID` and its
`["Operations", "<scheduledEventID>"]` component path before converting.
## Why?
Preparation for the cross-framework Nexus completion fallback (#11035),
where a completion whose token targets one framework must be retried
against the other after a rebuild (reset or conflict resolution) flips
the operation's framework.
## How did you test it?
- [x] built
- [ ] run locally and tested manually
- [ ] covered by existing tests
- [x] added new unit test(s)
- [ ] added new functional test(s)
## Potential risks
Low — additive, and only invoked by #11035. The one coupling to watch:
the converter encodes the CHASM `Operations` map field name and
`WorkflowArchetypeID`; a change to the workflow component's layout must
be reflected here.
