v10.7.0

The published client had no idea the platform could be held, so on the five
lanes that run on our machines a reader met either a bare status code or an
honest refusal that then sent them to a page answering 503. That is what
makes someone conclude the product is broken.

• A held lane now answers one shape on extension_publish,
  extension_release_promote, extension_submit,
  extension_project_create, extension_shares, extension_preview_web
  and the registry reads behind extension_release_status: status
  platform-held, error.platformCode set to PLATFORM_NOT_OPEN, and a
  message carrying the condition, what still works, and a way back.
• What still works is the part that was missing. Creating, developing and
  packaging an extension run on your own machine, they are free forever, and
  the hold does not touch them, so extension_create, extension_dev,
  extension_build, extension_manifest_validate and extension_doctor
  are named in the refusal and repeated in value.stillWorks.
• A held refusal may not point at a held surface, so the only link it
  carries is templates.extension.dev, the one surface that stays open,
  and no refusal names a date.
• Registry reads no longer collapse a non-ok response to
  <url> returned <status>. The body is read once and its message travels
  with the result, so a refusal the platform wrote reaches the reader
  instead of a number. A held read is answered without buying an access
  grant first, because a shut lane is not an auth problem.
• The hold is recognised by the code field and the x-extensiondev-hold
  header rather than by matching the sentence, so the wording can change on
  the server without a client release.