v0.9.0

Added

• refs tells you when a newer version is published. refs sync and refs doctor ask npm at most
  once a day and cache the answer; refs sync mentions a newer release in its warnings, and
  refs doctor reports it as a cli-update check. refs --version is untouched — it stays exactly
  one version line on stdout, because the skill's capability gate and any script parse it.

  Both switches live in [updates] in config.toml and default to on: check governs the registry
  request everywhere, notify the routine path only. notify = false with check = true is
  "don't interrupt me, but answer when I ask" — refs sync neither asks nor mentions, refs doctor
  still does both. REFS_UPDATE_CHECK overrides check (0 off, 1 on), and the check is off in
  CI. The table is absent from a config that wants the defaults, and refs never writes one.

  Nothing about it is load-bearing: an unreachable registry, a malformed answer or an unwritable
  cache all mean "we don't know" and are never reported as a fault. The registry host is hardcoded
  rather than read from npm configuration, only a plain x.y.z is accepted from the response, and
  the update command is printed for you to run — refs does not install itself.

Fixed

• A ref can be recorded without a tag_format. Finalizing an add used to reject a proposal whose
  tag_format_candidate was null, which left one option for a repository that publishes no tags:
  invent a convention. A real user hit this and was asked to confirm v{version} for two
  repositories that have no tags at all — a claim nobody had verified, written into config.toml
  where later agents read it as fact. The candidate now survives finalize as an absent field.

  refs tag is the only command that reads it, and it exits 3 (validation) when there is none,
  naming the ref — or the package, with the --package form of the fix. The distinction from 4
  carries information: 3 means this ref cannot resolve any version, 4 means this particular
  version was never tagged. The skill's add flow gained an explicit branch for the null case, so
  an agent reports the absence instead of proposing something to fill the gap.

  A format already recorded can only be removed by editing config.toml directly; refs edit can
  set one but has no way to unset it.