update the JavaScript version policy to ES2025 (after June 2030)

[erwindon]

Is your feature request related to a problem? Please describe.
Start using features from this JS version

Describe the solution you'd like
Start using useful features from this JS version.

The 16th edition of ECMAScript released in 2025.[42] It adds the following:

• The Iterator object which can wrap iterators like Array and provides a functional interface with lazy evaluation.
• Promise.try: call a method which may or may not be a promise as a promise
• New Set methods: Set.intersection, Set.difference, Set.symmetricDifference, Set.isSubsetOf, Set.isSupersetOf, Set.isDisjointFrom
• RegExp.escape function to escape a string so it can be concatenated together with a regex pattern.
• Importing JSON files directly as modules
• Float16Array along with related TypedArray methods

Additional context
Update:

• docs/README.md (ecmaVersion)
• eslint.config.js
• any JS code
• upgrade container base images (unrelated but this is a good opportunity)
• docker image description at https://hub.docker.com/repositories/erwindon