v0.9.0

Add Elasticsearch connector + site a11y audit fixes

- New elasticsearch connector (group Data, search/logs): list indices, get
  mapping, search (Lucene query); index document gated behind Writer; optional
  basic auth (works on unauthenticated clusters too); --manifest +
  --test-connection. Wired into workspace, both CI bin-lists, app embed,
  registry (now 15), site, README.
- Site a11y (from audit, contrast already all-pass): screen-reader live region
  announces suggestion count + no-results; aria-label on the suggestions
  listbox; 44px touch targets on coarse pointers (lang/filter/nav/suggest);
  sr-only utility. 23 E2E green; app compiles with Elasticsearch embedded.