Migrate category, report, rate, and digest persistence from Art to IPF

[Copilot]

This PR moves the lowest-risk persistence slice off the legacy Art layer: category, report, rate, and digest. It keeps existing module entry points and admin flows intact while removing direct Art dependencies from the migrated classes.

• IPF persistence migration

  • Convert Category, Report, Nrate, and Digest objects to IPF-backed objects.
  • Convert the corresponding handlers from ArtObjectHandler/custom object handlers to icms_ipf_Handler.
  • Override table/class mapping where needed so existing bb_* tables and public handler names continue to work.

• Handler compatibility

  • Preserve current call patterns such as create(), get(), insert(), delete(), getAllCats(), getAllReports(), and getAllDigests().
  • Keep category permission templating and cascading deletes in handler logic.
  • Replace Art-specific orphan cleanup with local SQL-based cleanup for migrated handlers.

• Admin CRUD alignment

  • Update report admin processing to work cleanly with the migrated report handler and sanitized posted IDs.
  • Refactor vote admin listing/deletion to use the rate handler instead of direct SQL, including joined topic title lookup and rating summary helpers.
  • Keep existing category and digest admin pages operating against the migrated handlers without changing their entry points.

• Regression guardrail

  • Add tools/ipf-migration-smoke.php to exercise the migrated CRUD paths and assert that the migrated class files no longer depend on Art.

Example of the new handler shape:

class IforumRateHandler extends icms_ipf_Handler
{
    function __construct(&$db)
    {
        parent::__construct($db, 'rate', 'ratingid', '', '', basename(dirname(__FILE__, 2)));
        $this->table = $db->prefix('bb_votedata');
        $this->className = 'Nrate';
    }
}