Implement "Settings" page that displays app version

[eecavanna]

Summary of changes

Main feature

• Introduced a new third-party dependency (i.e. an NPM package called vite-plugin-package-version) which reads the version property from the package.json file and makes it available via import.meta.env.PACKAGE_VERSION
• Added a config property that consumes import.meta.env.PACKAGE_VERSION and exposes it to the rest of the code base as config.APP_VERSION
• Replaced the placeholder "Settings" page with one that has a list-based layout
• The "Settings" page shows the app version number

Other changes

• Added developer instructions on introducing new environment variables
• Added TypeScript type information for the properties of import.meta.env

Screenshots

Light theme:

Dark theme:

Notes

This PR is about displaying the app version. It is not about maintaining/managing/defining the app version.

[eecavanna]

GitHub will only allow me to specify a single reviewer (as @pkalita-lbl found recently).

FYI: @pkalita-lbl and @yxu-lanl, I am ready for this to be reviewed. Today's Saturday. I don't expect it to be reviewed until next week.