feat(packageFiles): fail if a "prepare" npm script is defined

[mcm1957]

What changed

Extends validatePackageFiles() (the tests.packageFiles check) with a new test that fails if a prepare script is defined in the scripts section of package.json.

Why

A prepare npm script runs automatically on every npm install of the adapter — including installations by end users. This can break installations (e.g. if it invokes build tooling or dev-only dependencies that aren't present in a production install), so adapters should not ship one.

Details

• The check lives in the existing Check contents of package.json describe block and mirrors the style of the neighbouring dependency checks (guards with isObject, throws an AssertionError with the offending value included).
• A missing scripts section passes fine.
• Added a CHANGELOG.md entry under WORK IN PROGRESS.
• Regenerated build/tests/packageFiles/index.js to match.

npm run check and npm run lint both pass.

🤖 Generated with Claude Code

[mcm1957]

@GermanBluefox
I suggest to let standard tests fail if a prepare script is present. I do not know any adapter which need to use a prepare script (prebuild, prepackage etc are allow although they are not used widely. Only prepare can have sideeffets at target system (instaling all devDependencies) and is not needed. Code can und should be built at least when creating th package.

Please review an merge if OK from your side