Use changesets instead of beachball

[JonasDov]

closes #1125

• Replaced beachball with changesets.
• Packages in the repo from now on will be released with an automated release pr.
• Added CI protection against manual public package version changes. Version changes should be done with release PRs.
• Added changeset generation script that:
  • Rejects empty changesets.
  • Prefixes single-package changesets with the package name: allows codeowners to be assigned correctly.
  • Prefixes multi-package changesets with "multi-package".
• Updated CODEOWNERS.

New release Workflow

• Contributors run pnpm change for changes requiring a release.
• Changesets are reviewed with the feature PR; changes without releases need none.
• After merge to master, Changesets creates or updates a release PR with versions and changelogs.
• Merging the release PR builds and publishes packages to npm.

Release PRs update package CHANGELOG.md files with package-specific CODEOWNERS rules. All release PRs require approval from VCR reviewers. For tree-widget, property-grid, and quantity-formatting, Presentation reviewers may approve instead.

PRs containing changesets require VCR approval. Presentation reviewers may approve single-package changesets for tree-widget and property-grid, or any changeset marked multi-package.

[Copilot]

Pull request overview

This PR migrates the repo’s release tooling from Beachball to Changesets, introducing a Changesets-based contributor workflow, automated release PR generation/publishing, and CI safeguards to prevent manual version edits on feature PRs.

Changes:

• Replaced Beachball scripts/config/pipeline with Changesets CLI + GitHub Actions release workflow.
• Added helper scripts for changeset creation (with filename prefixing for CODEOWNERS) and CI checks preventing manual public package version changes.
• Updated contributor guidance and CODEOWNERS to reflect the new changeset/release process.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
scripts/create-changeset.js	Runs changeset add and renames the generated file to include a package-based prefix for CODEOWNERS routing.
scripts/check-package-versions.js	CI helper to reject manual version changes for public packages outside the Changesets release PR flow.
package.json	Removes Beachball commands and adds Changesets-based change and release scripts plus version-check script.
pnpm-lock.yaml	Updates lockfile to remove Beachball and add Changesets (and related dependency graph updates).
CONTRIBUTING.md	Updates contributor workflow documentation to require changesets for releasable changes and describes the new release process.
.github/workflows/ci.yml	Replaces Beachball “check change files” job with a version-change protection job.
.github/workflows/changeset-release.yml	Adds Changesets automation to open/update a release PR and publish to npm when merged.
.github/CODEOWNERS	Updates ownership rules for generated changeset files and package changelogs.
.changeset/README.md	Adds repository-local documentation for the .changeset directory purpose and workflow.
.changeset/config.json	Adds Changesets configuration including base branch and changelog generator wiring.
.changeset/changelog-github.mjs	Custom changelog generator that attempts to link changelog lines to PRs via GitHub API.
beachball.config.js	Removed Beachball configuration.
beachball.config.dev.js	Removed Beachball dev-release configuration.
.pipelines/publish.yaml	Removed Beachball-based publish pipeline.

Files not reviewed (1)

• pnpm-lock.yaml: Generated file

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[Copilot]

Pull request overview

Copilot reviewed 15 out of 16 changed files in this pull request and generated no new comments.

Files not reviewed (1)

• pnpm-lock.yaml: Generated file

Suppressed comments (1)

scripts/check-package-versions.js:16

• base defaults to origin/master, which can be missing in local clones (or any environment without that remote ref), causing git diff origin/master...HEAD to throw and the script to fail even when there are no version changes. Since this repo’s base branch is master, defaulting to master is more robust; CI already passes an explicit base SHA.

const base = process.argv[2] ?? "origin/master";

[github-actions]

Tree-Widget benchmark

Benchmark suite	Current: 1a05687	Previous: e4c6fe1	Deviation	Status
models tree creates initial filtered view for 50k target items	1108 ms	1059 ms	4.63%	〰️
models tree creates initial filtered view for 50k target items (P95 of main thread blocks)	137 ms	97 ms	41.24%	〰️
models tree validates categories visibility for imodel with 50k categories	12132 ms	11119 ms	9.11%	〰️
models tree validates categories visibility for imodel with 50k categories (P95 of main thread blocks)	98 ms	84 ms	16.67%	〰️
models tree changing model visibility changes visibility for 50k elements	3518 ms	3096 ms	13.63%	🚨
models tree changing model visibility changes visibility for 50k elements (P95 of main thread blocks)	129 ms	123 ms	4.88%	〰️
models tree changing category visibility changes visibility for 50k elements	3451 ms	2625 ms	31.47%	🚨
models tree changing category visibility changes visibility for 50k elements (P95 of main thread blocks)	30 ms	0 ms	3000%	〰️
models tree changing per-model-category override changes visibility for 50k elements	3466 ms	2706 ms	28.09%	🚨
models tree changing per-model-category override changes visibility for 50k elements (P95 of main thread blocks)	0 ms	0 ms	0%	🟰
models tree changing element visibility changes only parent nodes visibility with 50k elements	5299 ms	4817 ms	10.01%	🚨
models tree changing element visibility changes only parent nodes visibility with 50k elements (P95 of main thread blocks)	84 ms	96 ms	-12.50%	〰️
categories tree creates initial filtered view for 50k items	1714 ms	1424 ms	20.37%	🚨
categories tree creates initial filtered view for 50k items (P95 of main thread blocks)	462 ms	278 ms	66.19%	🚨
categories tree changing definition container visibility changes visibility for 50k subCategories	2823 ms	3160 ms	-10.66%	✅
categories tree changing definition container visibility changes visibility for 50k subCategories (P95 of main thread blocks)	52 ms	41 ms	26.83%	〰️
categories tree changing definition container visibility changes visibility for 50k categories	6051 ms	5719 ms	5.81%	〰️
categories tree changing definition container visibility changes visibility for 50k categories (P95 of main thread blocks)	128 ms	131 ms	-2.29%	〰️

This comment was automatically generated by workflow using github-action-benchmark.

[aruniverse]

what about for dev builds for tree-widget/next

[JonasDov]

This PR includes all changes which are needed for master branch releases to work. After merging master to next I will create a separate PR for updating the config & whatever else is necessary for releases on next to work (those changes will live on next).