Summary

Add Node 26 to the runner matrix and start building under it.

Linked issue

N/A

Changes

N/A

Checklist

• Tests added or updated (or N/A with reason)
• Docs / types updated if public API changed (index.d.ts and index.d.cts)
• No breaking changes (or called out explicitly above)

Summary by cubic

Expands CI to Node.js 26 across all workflows and switches publishing to staged mode. Also updates HTTPS proxy tests to use localhost for Node 26 TLS compatibility.

Description

• Summary of changes
  • Bump CI to Node 26.x; add 26 to matrix [20, 22, 24, 26]
  • Switch publish step to npm stage publish
  • Update HTTPS proxy fixtures to use localhost instead of 127.0.0.1
• Reasoning
  • Validate compatibility on Node 26
  • Reduce release risk with staged publishing
  • Fix test hostname/TLS expectations on Node 26
• Additional context
  • Workflows updated: CI, release, publish, bundle-size, lockfile-lint, reproducibility
  • Uses actions/setup-node and actions/checkout

Docs

• Add Node 26 to supported versions in /docs/
• Update release guide to use npm stage publish

Testing

• Modified unit tests: HTTPS proxy paths now use localhost; no new tests added
• CI runs existing suites on Node 26

Semantic version impact

• Patch: CI, publishing, and test-only changes; no runtime or API changes

^{Written for commit 68a3ff9. Summary will update on new commits. Review in cubic}