Ensure CML is compliant with the type annotations proposal

[littlespex]

The type annotations proposal (spec) allows JS engines to strip out type declarations and run Typescript without a build step. The CML code base, including its internal build scripts, already aligns (mostly) with this proposal. This should allow us to remove dependencies like tsx once we move to a version of node that supports "type stripping". In order to fully support this proposal we should:

• Upgrade Node dev dependency to >=23.6.
  • Enforce this requirement using devEngines property:

    "devEngines": {
      "runtime": {
        "name": "node",
        "version": ">=23.6.0",
        "onFail": "error"
      }
    },
    

• Validate the codebase isn't using a non-supported feature via lint rules
  • https://github.com/JoshuaKGoldberg/eslint-plugin-erasable-syntax-only.
• Update to Typescript version 5.8
  • Update tsconfig.json to set erasableSyntaxOnly