/boards and the terminal's Flow dialog show each reviewer's reviews in flight, counted only from repositories the reader can see #4733

Replaces the display half of #4486.

Done:

• [ ] /boards and the terminal's Flow dialog show, per reviewer, how many review runs are in flight.
• [ ] Counts are scoped to the reader: only repositories the reader can see are counted. A test where a guest reads the page while a review runs on a private repository shows no count from it; it fails if the scope is removed.
• [ ] The count reuses reviewLoad from src/crew/review.ts (add it there if it is not on main yet) so routing and display cannot drift.
• [ ] §5 components only; bun scripts/design-lint.ts clean. README.md's /boards section names the line.

Files: src/crew/review.ts, src/web/pages/boards.ts, the terminal's Flow dialog, a test, README.md.

Parked by the crew: the check failed ("RepoSource: one repository, two places to read it from > a mirror reports its stages in order and ends holding the repo") and the decider saw no point in another try (pull #4737 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.