Release with changesets and the shared toolchain, not np

RELEASE.md for this family of repos prescribed a bare `np patch` -
literally always patch, decided on release day, with no changelog coming out
of it at all. Changesets moves that decision into the PR that makes the
change, and writes the changelog from it.

The release script is @datocms/release-toolchain, the same one the four
monorepos run, installed by git tag and never published to npm. In a repo
that is one package it tags vX.Y.Z, which is what np tagged too, so the tag
history is continuous.

Claude-Session: https://claude.ai/code/session_01XaYAhzmiJwysZeq1XC5xrQ

Author: Stefano Verna

.changeset/README.md

@@ -0,0 +1,36 @@
+# Changesets
+
+This folder holds the pending release notes for the next version.
+
+Whenever you change something worth mentioning in a release, run `npx changeset`
+and answer the two prompts (which packages, and whether it's a patch/minor/major).
+That writes a small markdown file here, which you commit along with your changes.
+
+At release time `npm run release` consumes every pending file: it computes the
+resulting versions, updates the `package.json`s and the `CHANGELOG.md`s, and
+deletes the files.
+
+## Which bump level?
+
+- `patch` — bug fixes only. It's the clearest signal in semver ("nothing new,
+  just a fix"), so we don't spend it on anything else.
+- `minor` — new public API surface.
+- `major` — public API was removed or renamed.
+
+## Prereleases
+
+`npm run release:next` publishes under the `next` dist-tag, leaving `latest`
+untouched. It works in two modes:
+
+- **as-is** — the pending changesets produce a normal version (say `4.1.0`)
+  which is published under `next` instead of `latest`;
+- **real prerelease versions** — run `npx changeset pre enter next` first and
+  the same command produces `4.1.0-next.0`, `4.1.0-next.1`, … That mode is
+  recorded in `.changeset/pre.json`, which you commit. Run
+  `npx changeset pre exit` when the line is done.
+
+Either way the GitHub release is marked as a prerelease, so it never becomes
+the repository's "Latest release".
+
+`npm run release` refuses to run while `.changeset/pre.json` exists, so a
+forgotten pre mode can't quietly turn a real release into a prerelease.

.changeset/config.json

@@ -0,0 +1,11 @@
+{
+  "$schema": "https://unpkg.com/@changesets/config@4.0.0/schema.json",
+  "changelog": "@changesets/cli/changelog",
+  "commit": false,
+  "access": "public",
+  "baseBranch": "main",
+  "fixed": [],
+  "linked": [],
+  "updateInternalDependencies": "patch",
+  "ignore": []
+}

README.md

@@ -297,6 +297,25 @@ reported it before it is released.
 Previews are throwaway: they are never published to npm, and the URL stops
 resolving after a while. Never commit one to a `package.json` that ships.
 
+## Releasing (maintainers)
+
+Every user-visible change needs a changeset: run `npx changeset` from the repo
+root in the same PR, pick the bump level (`patch` is for bug fixes only, new API
+surface is `minor`) and commit the file it writes under `.changeset/`. That is
+where the changelog entry comes from, and it is where the bump level is decided
+— not on release day. See [`.changeset/README.md`](.changeset/README.md).
+
+To release, from an up-to-date, clean `main`, run `npm run release`. It
+builds and tests, applies the pending changesets — bumping the version and
+writing `CHANGELOG.md` — publishes to npm, and only then tags `vX.Y.Z`, pushes,
+and creates a GitHub release whose notes come straight from that changelog
+entry. An interrupted release is resumed by re-running it, never undone. Use
+`npm run release:next` for a prerelease under the `next` dist-tag.
+
+The script is
+[`@datocms/release-toolchain`](https://github.com/datocms/release-toolchain),
+shared with every other DatoCMS repository and pinned here by tag.
+
 ## License
 
 This project is licensed under the MIT License.