chore: add Node 24, 26 to engines

[pacostas]

Summary

This PR updates the Node.js version support in npcheck to align with the current active and maintenance LTS versions.

Changes

• Added: Node.js v24 (active LTS) and v26 (current) to engines.node in package.json
• Maintained: Node.js v22 (maintenance LTS) support
• Updated: engines.node from >=22 to ^22 || ^24 || ^26 for explicit version support

Notes

• CI workflows already correctly test against Node.js 22.x, 24.x, and 26.x
• Release workflow already uses Node.js 24 (latest active LTS)
• package-lock.json regenerated with npm install
• All tests pass

[lholmquist]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues

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