Outside and from-app reports are always fenced in a crew brief, whoever wrote them #10555

Part of #10441, the second piece of #10451. Today the brief says the report is "inside the fence below", but it fences the body only when its author is marked a reader.

Done:

• [ ] Outside reports and from-app reports are fenced whoever wrote them.
• [ ] A test in test/brief-injection.test.ts for each kind fails on today's main.

Files: src/crew/brief.ts, test/brief-injection.test.ts

Planner: replaced by #11086. The same fence, rewritten so it starts fresh from today's main, and it adds that a body holding the closing marker stays inside the fence.