Stencil language selector implementation guide

Adds a new implementation guide for building a storefront language selector in Stencil themes — useful for third-party themes and custom themes based on Cornerstone versions earlier than 6.19.0, which already ships the selector natively.

  • language_selector object reference — Documents the properties Stencil exposes on every page (active_language_code, languages, and per-language code, switch_url, is_active)
  • Handlebars partial and header include — Step-by-step example showing how to render the selector and gate the include with {{#and language_selector language_selector.languages.length '>' 1}} so it only appears when more than one active language is configured
  • Locale-code resolution — Pattern for resolving raw locale codes to native language names using Intl.DisplayNames

For details, see Storefront Language Selector.