This PR only touches CI configuration (no published package changes),
so it carries an intentionally empty changeset. This satisfies the new
`changeset status` gate, which requires every PR with changes to either
declare a release or explicitly opt out via an empty changeset.

https://claude.ai/code/session_01HWaRWqpMHzzeTSJeqTeV75

`changeset status` couples two behaviors: validating that changesets
reference real packages, and requiring every PR with changes to include
a changeset. Only the former is needed for #250, and the latter forced
empty changesets on CI/docs/chore PRs (and behaved inconsistently between
local and the PR merge-ref checkout).

changesets has no config flag to disable the "changed but no changeset"
error, so replace the step with scripts/validate-changesets.mjs, which
uses @changesets/get-release-plan (already a devDependency) to assemble
the release plan. That throws on a changeset referencing a missing
package (catching #247) but does not require a changeset to exist and
needs no git history -- so fetch-depth: 0 and the empty changeset are
both dropped.

https://claude.ai/code/session_01HWaRWqpMHzzeTSJeqTeV75

Revert the custom validation script in favor of `changeset status`, which
requires a changeset when a versionable package changes (the behavior we
want) and still fails on changesets referencing a missing package (#247).

Two adjustments make it robust:

- Set `privatePackages.version: false` in .changeset/config.json. By
  default changesets treats private packages as versionable, so changes
  to the private demo app (example-app) and config packages demanded a
  changeset. Those are never published, so they are now exempt; the six
  published @infinitered/* modules still require one.

- Run the changeset check before `yarn lint`. Lint runs `prettier
  --write`, which reformats drifted files in place and made changesets
  think example-app changed. Checking the pristine, just-checked-out tree
  avoids that phantom change.

Note: root-level files (.github, .circleci, etc.) are not part of any
workspace package, so CI/config-only PRs never require a changeset.

https://claude.ai/code/session_01HWaRWqpMHzzeTSJeqTeV75

CI ran `yarn lint`, whose example-app script does `eslint --fix` and
`prettier --write`, silently reformatting files in the runner instead of
failing on drift. Make CI verify instead of fix:

- Add `lint:ci` to example-app (eslint without --fix, prettier --check)
  and a matching `format:check` script.
- Add root `ci:lint` that lints the modules via turbo (their
  `expo-module lint` is already non-mutating) and runs example-app's
  check. No --no-cache: the example-app check runs outside turbo and
  module lint is non-mutating and input-keyed, so turbo's cache stays
  correct.
- Point the CI workflow at `yarn ci:lint`. `yarn lint` still auto-fixes
  locally.
- Format the two drifted example-app files so the check passes.

https://claude.ai/code/session_01HWaRWqpMHzzeTSJeqTeV75

The job name is what branch protection's required-status-check rule
matches on. Use a short, stable 'verify' instead of a descriptive
sentence so the rule doesn't need re-updating if the description changes.

https://claude.ai/code/session_01HWaRWqpMHzzeTSJeqTeV75