Proposal: add a "multi-role paper review" reference trace

[Joe-rq]

Hi maintainers — I would like to gauge interest in contributing a new reference
trace before doing the build work.

Background

I have been building PaperSwarm
on top of Flowtrace — a multi-role academic peer-review workflow for research
drafts. A paper is parsed, a reviewer set is selected by paper type, independent
reviewer roles run in parallel, conflicts are detected, a revision plan is
produced, and a Worker/Verifier loop verifies the revision.

What I would contribute

A new builder under scripts/examples/ (e.g. paper-review/) that walks the
full CLI lifecycle and demonstrates Flowtrace capabilities that the current
six reference traces do not cover well together:

• fan-out / fan-in — 4 reviewer roles (editor, methodologist, domain
  expert, devil's advocate) run as independent steps, then fan into a single
  conflict step. None of the existing data-analysis traces have a wide
  many-to-one fan-in like this.
• blocked → resume — the conflict step blocks awaiting author
  adjudication between disagreeing reviewers, then resumes (analogous to
  assumption_check in iris-analysis, but for multi-source disagreement).
• error → retry — the revise step's Verifier rejects an incomplete
  revision, triggering a retry loop.

Questions before I start

1. Is a non-data-analysis reference trace welcome? Most existing traces
   are data pipelines; only tailored-resume and spring-demo are not. A
   multi-agent review DAG would extend that non-data coverage.
2. Fixture domain — I am leaning toward a short, fictional
   social-science / education paper so only the 4 base roles are needed and
   the fixture stays small. Any preference?
3. Scope — I have a 9-step working version (already validated end-to-end
   with a real run). Does that size fit the "land in an hour or two" spirit
   of the existing examples?

Happy to adjust the theme/scope to whatever fits the project best.