• Applies a search filter to a list container, showing/hiding child rows based on their data-search-name attribute. Pure and Foundry-free.

    A row matches when:

    • query is blank → always visible (all rows revealed).
    • rgx is provided → the regexp tests the normalised search-name.
    • otherwise → the normalised search-name includes the normalised query.

    Normalisation is done via sohl.i18n.normalizeText (case-insensitive, ASCII).

    Parameters

    • query: string

      The raw search string from the input element.

    • rgx: null | RegExp

      Optional compiled regexp (from the Foundry SearchFilter).

    • content: null | Pick<HTMLElement, "querySelectorAll">

      The container element to search inside; no-op if null.

    Returns void