Searchable country select

[mdanilowicz]

Technical TODO

Summary

Replace the static country dropdown in vue-starter-template with a searchable FormCountrySearchSelect component that loads countries from the Store API on demand, supports search and infinite scroll, shows flag icons, and integrates with existing address/state validation.

Problem

The starter template used FormDropdownField with useCountries() to render a full country list upfront. That approach:

• Loads all countries at once, which does not scale well for large country lists
• Offers no search/filter UX for long lists
• Does not align with criteria-based Store API reads (including cacheable GET when cacheableReads is enabled)
• Validates state/province as required based on country ID alone, without knowing whether the selected country actually has states