Refactor AlpineJS specific attribute scopes

This commit

1. scopes AlpineJS specific attributes `meta.directive`

2. scopes attribute name parts after periods (e.g.: `x-on:click.prevent`)
   `storage.modifier`.

to align with other template syntaxes like Datastar, Svelte or Vue.

Update CI

1. Upgrade to actions/checkout@v4
2. Add stable ST builds to test against

README: Fix least required ST build