Add two rebindable search behaviors consumed across the app catalog:
- std-app-search: SEARCH event -> server-side filtered fetch (str/includes on
  a configurable field) -> results view -> clear. Wraps a host content trait
  via config.idleContent; emit-less INIT fetch; trigger event APP_SEARCH.
- std-autocomplete: inline typeahead -> filtered fetch -> suggestion list ->
  AUTO_SELECTED { id }.

Both validated headless via @almadar/runtime processEvent + validateEventPayload.

(Working tree also carries in-progress infra atoms std-status-lifecycle +
std-notify-on-event from a concurrent process; they validate clean and ride
along in this patch.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>