chore(ci): keep CURRENT_STATE current automatically from the release workflow #151

CURRENT_STATE.md has gone stale after three consecutive releases (0.4.3,
0.4.4, and the earlier 0.3.2), each needing a manual catch-up PR (#146, #150).
The cause is structural: the changesets release PR bumps package.json and
CHANGELOG.md but never touches CURRENT_STATE.md, so the version there drifts
every cycle.

Fix

Fold a CURRENT_STATE.md update into the changesets version step, so it rides
the existing "version packages" PR. That PR already gets CI and a human merge, so
there is no direct push to protected main and no separate PR.

Concretely:

• A small dependency-free Node script, scripts/update-current-state.mjs, run
  right after changeset version. It reads the freshly bumped version from
  packages/toolkit/package.json and the top entry of
  packages/toolkit/CHANGELOG.md, then updates two machine-maintained spots in
  CURRENT_STATE.md: the package status table version, and an auto-managed
  release-log block delimited by HTML-comment markers.
• The script is idempotent: running it twice for the same version does not
  duplicate the entry.
• Wire it via a root script, version:packages, and point the workflow's
  version: command at it.

Editorial prose (the "Current Version" narrative) stays hand-written, since a
per-release sentence is human commentary, not a fact to automate. Only the two
factual fields are machined.

Acceptance

• Merging a "version packages" PR lands the release-log entry and the table
  version in the same commit, with no manual step.
• A unit test covers the parse-and-update logic against a fixture.
• No new runtime dependency; the script uses only Node built-ins.