[izzetemredemir]

Closes #784. Fixes #761.

Problem

New projects, examples and UI scaffolds depend on o1js ^2.*. After Mesa, the networks only accept transactions and verification keys from o1js 3.x. Details are in #784.

Changes

• templates/project-ts/package.json, src/lib/project.js (UI scaffolds) and the CLI's package.json: o1js ^2.* → ^3.1.0.
• package-lock.json: regenerated with npm install --package-lock-only. Only the o1js subtree changes (o1js 2.0.0 → 3.1.0 and its dependencies).
• engines.node → >=22.19.5 in the template and the CLI, the floor o1js 3.1.0 declares. README requirement updated.
• CI: the generated project's workflow and this repo's test-and-publish, nightly-e2e-ci-tests and pkg-pr-new-publish workflows move from Node 18/20 to 22 (unit tests, publish) and 22/24 (E2E). release.yml only runs npm version and stays on 18.
• npm run coverage fails in boilerplate repo #761: the template's coverage script runs node --test --experimental-test-coverage like test. The unused @babel/* and ts-jest devDependencies, babel.config.cjs and the jest ESLint env are removed. If you'd rather take npm run coverage fails in boilerplate repo #761 separately, I can drop this part.
• CHANGELOG entries under Unreleased.

mina-signer stays on ^3.0.7. The CLI only uses it for genKeys(), which doesn't depend on the network.

Tests

On o1js 3.1.0:

• CLI: npm ci from the new lockfile, npm run build, npm run coverage. 9 suites, 247/247 on Node 22.19.0 and 24.21.0. eslint . reports no problems. prettier --check passes on the changed files. src/lib/constants.js already fails prettier --check on main, and this PR doesn't touch it.
• zk project o1js3check --ui none: installs o1js 3.1.0. npm run build, npm test (2/2: AddZkProgram proof settled on Add), npm run coverage (2/2) and npm run lint pass.
• zk example sudoku and zk example tictactoe, as the CI jobs run them: npm run test (2/2 each), npm run build and npm run start pass.
• The template tests also pass on Node 18.20.8 and 20.19.2. The engines bump follows o1js's declared support range. It doesn't fix a runtime failure.

Not run locally: the Next.js/SvelteKit/Nuxt scaffolds and the Lightnet E2E suites. The Next.js scaffold aliases node_modules/o1js/dist/web/index.js, and that file is still there in 3.1.0. The smoke E2E jobs use the compatible-latest-lightnet and master-latest-lightnet images, and o1js 3 transactions need those images to run Mesa. I couldn't check that.

This PR and #782 (Release v0.23.1) both touch CHANGELOG.md and package-lock.json. Whichever lands second will need a rebase, and I'll do it on this side.

[dkijania]

Hey @izzetemredemir. Thanks for this contribution. I have one big ask to split this PR as IMHO it tackles 3 different things (though bump of node can be considered as precondition to bump o1js). I would recommend introducing 3 pr:

1. Coverage fix
2. Bump node
3. Bump o1js

Thanks !