Built-in star rating widget for integer fields

[dennisklappe]

Integer fields render as a number input, which is a weak fit for ratings: editors have to know the scale and type a digit, with no visual cue for the range and nothing stopping a typo.

Proposal: a built-in stars widget for integer and number fields, selected by setting a field's widget to "stars", with options.max for the star count (default 5). Click a star to set the rating, click the current one to clear it. The stored value stays a plain integer, so themes need no widget runtime. It reuses the existing widget and options plumbing (built-in widgets use a bare name, plugin widgets keep the pluginId:widgetName form).

There is a working branch (admin component, FieldRenderer wiring, a small core type and doc tweak, tests, changeset) ready to PR if this direction is welcome. Would you accept this as a native widget, or do you prefer rating UIs to stay in userland plugins?