update-node-v18: nvmrc now v18.18.2

[daveseah]

This updates our official node target to v18.18.2, which is the latest version of the LTS v18 release. This is supported into April 2025. The version is stored in the .nvmrc file in the repo.

When updating node versions, it's generally a good idea to run the following commands again:

npm ci

as the package-lock.json file that contains dependencies has changed. There should be no issues since we were already on the v18 branch (previously, v18.16.0). We are making this change across all projects.

TO USE / TEST

1. Pull the branch
2. Make sure you are using the Visual Studio project file: netcreate-itest.code-workspace. This is how you should be making changes to netcreate, as the code workspace file contains important configuration settings that are only active.
3. important rm -fr node_modules before running npm ci
4. run netcreate normally, report any weird issues or crashes. Describe what you expected to happen, and include screenshots of what you saw instead (identify where to look so)

[benloh]

Works!