docs: Update Node.js version requirement to 24.0.0

[lawrence6140791]

Summary

Update the Node.js version requirement from 18.0.0 to 24.0.0 across SDK documentation to match the package.json engine requirement.

Key Changes

• nodejs/README.md: Update Requirements section to Node.js >= 24.0.0
• .github/copilot-instructions.md: Update test assumptions to node >= 24

Context

• The nodejs/package.json engines.node is >=24.0.0
• Documentation now reflects the actual minimum Node.js version required
• Ensures consistency across all documentation files

[Copilot]

Pull request overview

Updates the Node.js SDK documentation to match the minimum Node.js version enforced by the engines.node field in the Node package, keeping the README requirements accurate for users.

Changes:

• Bumped the documented Node.js requirement from >= 18.0.0 to >= 24.0.0 in the Node.js SDK README.