Stop-and-document outcome for issue #680's final runtime wiring. The
serving turn has no lawful in-turn ContemplationResult or provider: the
sole QUESTION_NEEDED producer (generate.contemplation.contemplate) is an
off-serving growth organ that runtime is forbidden to call, and no
plumbing carries its artifact into the turn. Wiring is deferred to a
lawful acquisition slice; chat/runtime.py is left untouched.
