Min dev node version

[derekpierre]

Type of PR:

• Bugfix
• Feature
• Documentation
• Other

Required reviews:

• 1
• 2
• 3

What this does:

• Node v18 is end-of-life, https://nodejs.org/en/about/previous-releases, and no longer works with vitest (our test suite). Update min dev node version to be 22. This a dev version update but does not enforce use of this newer version for users of the library i.e. library runtime might still work fine on Node 18.
• Other updates may be needed for node version 25 support since there was some removal of experimental webstorage in that version - src,lib,test: unflag --experimental-webstorage by default nodejs/node#57666. Not sure about all of the specifics, but for now node v25 is not used as part of CI, and node v24 is the cap.
• We also probably need to change the library to require newer node version for adopter usage, this can tackled in a separate PR; not sure about all of the side effects of this magnitude of change.

Issues fixed/closed:

• Fixes #...

Why it's needed:

Explain how this PR fits in the greater context of the NuCypher Network. E.g.,
if this PR address a nucypher/productdev issue, let reviewers know!

Notes for reviewers:

Those with more Typescript knowledge can comment on best practices here.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (signing-epic@a6efe66). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff               @@
##             signing-epic     #773   +/-   ##
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  Coverage                ?   90.81%           
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  Files                   ?       98           
  Lines                   ?     8629           
  Branches                ?      567           
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  Hits                    ?     7836           
  Misses                  ?      750           
  Partials                ?       43           

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[Copilot]

Pull request overview

This PR updates the repository’s development/CI Node.js baseline in response to Node 18 reaching end-of-life and incompatibilities with the current Vitest-based test suite.

Changes:

• Bump the dev Node version in .nvmrc from 18 to 22.
• Update GitHub Actions CI matrices to run on newer Node versions (main CI: 22/24; npm package check: 22).
• Adjust a Vitest mock call-site to avoid using Array.prototype.at() when retrieving the latest mock call.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
packages/taco/test/taco-sign.test.ts	Replaces .at(-1) with an index-based last-call lookup in a test.
.nvmrc	Updates local/dev Node version to 22.
.github/workflows/npm.yml	Updates the npm package validation job to run on Node 22.x.
.github/workflows/main.yml	Updates main CI Node matrix to 22.x and 24.x.

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