chore(node): bump from 18 to 22

[iainsproat]

Description & motivation

Node 18 is EOL in early 2025, and Node 22 is new LTS.

https://linear.app/speckle/project/remain-on-a-javascript-runtime-environment-with-long-term-support-31b50d0fdd9b/overview

Changes:

• bump all references to Node 18 to Node 22
• Fix minor capitalisation linting error in Dockerfiles (does not affect behaviour)

To-do before merge:

• test locally
• merge after SpeckleCon

Screenshots:

Validation of changes:

Checklist:

• My pull request follows the guidelines in the Contributing guide?
• My pull request does not duplicate any other open Pull Requests for the same update/change?
• My commits are related to the pull request and do not amend unrelated code or documentation.
• My code follows a similar style to existing code.
• I have added appropriate tests.
• I have updated or added relevant documentation.

References

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