[EngSys] Migrate all EngSys code from JS to TS

[mikeharder]

With node24 supporting type stripping by default, and type transformation with an experimental env var, we should migrate all the EngSys code from JS to TS.

• https://nodejs.org/docs/latest-v24.x/api/typescript.html

By default, we should start with just type stripping:

• https://nodejs.org/docs/latest-v24.x/api/typescript.html#type-stripping

Recommended tsconfig.json:

{
  "compilerOptions": {
     "noEmit": true, // Optional - see note below
     "target": "esnext",
     "module": "nodenext",
     "rewriteRelativeImportExtensions": true,
     "erasableSyntaxOnly": true,
     "verbatimModuleSyntax": true
  }
}

If we think it's worth it, we could enable expermental type transformation (eg enums):

• https://nodejs.org/docs/latest-v24.x/api/typescript.html#full-typescript-support

- uses: actions/github-script@v9
  env:
    NODE_OPTIONS: --experimental-transform-types