Add a use case and let the tool prove it

Situation

A command gained a behaviour and nobody wrote down what a person does with it. The documentation will drift the day it is written by hand, and a paragraph proves nothing.

Scenario

setup: installed
given:
  - 'Majordomus installed; the skeleton seeds the use-case section with no use case yet'
steps:
  - id: nothing-yet
    run: ['usecase', 'list']
    note: 'the section exists and is empty'
    expect:
      exit: 0
      stdout_contains: ['use cases: 0 in']
  - id: the-gaps
    run: ['usecase', 'coverage']
    note: 'every public command is a target; a fresh policy reports gaps and fails on none'
    expect:
      exit: 0
      stdout_contains: ['^command +doctor +0 +0 +0 +gap +advisory']
  - id: scaffold
    run: ['usecase', 'scaffold', '--for', 'command:doctor']
    note: 'a draft from what the registry, the fixture and the claims already know; nothing in it is verified'
    expect:
      exit: 0
      stdout_contains: ['wrote: \.ai/repo/use-cases/doctor-draft\.md']
  - id: validate
    run: ['usecase', 'validate']
    note: 'the draft resolves: its command, setup and category exist'
    expect:
      exit: 0
      stdout_contains: ['usecase validate: 0 failure']
  - id: run-it
    run: ['usecase', 'run', 'doctor-draft']
    note: 'the scaffolded scenario executes the real command in a disposable repository'
    expect:
      exit: 0
      stdout_contains: ['doctor-draft +pass']
  - id: still-a-gap
    run: ['usecase', 'coverage']
    note: 'a draft never counts; coverage moves when the use case is active'
    expect:
      exit: 0
      stdout_contains: ['^command +doctor +0 +0 +0 +gap']
then:
  - 'a use case is a file; everything else (the page, the links, the tally) follows'
  - 'a draft can run but cannot cover: status is authored, maturity is observed'

Outcome

usecase scaffold writes a draft with the facts the tool already has, usecase run executes its scenario against the real tool and records the evidence, and usecase coverage says what is still missing. The draft counts for nothing until it is made active.