🔧 [Refactor] NodeJS Version Inconsistency

[mahula]

🔧 Refactor

• Version 20.12.1 in .tool-versions

• Version 20 in backend/Dockerfile

• When seeding the backend using 20.12.1 from .tool-versions, we get warned about using an unsupported engine - requiring node: '>=22':

  npm WARN EBADENGINE Unsupported engine {
  npm WARN EBADENGINE   package: '@directus/sdk@19.1.0',
  npm WARN EBADENGINE   required: { node: '>=22' },
  npm WARN EBADENGINE   current: { node: 'v20.12.1', npm: '10.5.0' }
  npm WARN EBADENGINE }
  

It would help, if we recommend the NodeJS version to use in the documentation here and consistently use it.
For example we could rely on the latest LTS version of Node.js v22.19.0.
Or recommend to use the latest major version.