chore: upgrade Node.js from 18 to latest LTS (v24)

[Mahmoud-s-Khedr]

Summary

The project currently uses Node.js 18 (v18.8.0), which reached end-of-life in April 2025. Upgrading to Node.js 24 (current LTS) will bring security patches, performance improvements, and access to newer language/runtime features.

Files to update

File	Current	Target
.nvmrc	v18.8.0	v24.x.x (latest 24 LTS)
Dockerfile	node:18-alpine3.16	node:24-alpine
Dockerfile.railwayapp	node:18-alpine3.16	node:24-alpine
Dockerfile.test	node:18-alpine3.16	node:24-alpine

CI workflows (checks.yml, release.yml) use node-version-file: .nvmrc and will pick up the change automatically.

Acceptance criteria

• .nvmrc updated to latest Node 24 LTS patch version
• All three Dockerfiles updated to node:24-alpine
• CI passes (lint, unit tests, integration tests)
• Docker build succeeds locally

[vikashsiwach]

Hey @cameri , I would like to work on this issue

[phoenix-server]

Thanks for your interest, @vikashsiwach! 🙏 We have a fairness policy to ensure all community contributors get a chance at good first issues. I see you already have issue #390 (NIP-62 implementation) assigned. Once you complete that, we'd love to have you tackle another one. For now, we're distributing this issue to another contributor. Keep up the great work!

[Mahmoud-s-Khedr]

sorry, I'm currently working on this issue

[phoenix-server]

Thank you @Mahmoud-s-Khedr for this contribution! The Node.js 24 LTS upgrade and dependency updates have resolved 30+ security vulnerabilities. Great work!