docs(idaa): track contact_li_json_ext search gap + message sent to backend

- TODO__Agents.md: added task for contact search — backend to whitelist
  contact_li_json_ext in event search, frontend to add OR condition in
  search__event() and update local IDB fast-path filter. Blocked on backend.

- CLIENT__IDAA_and_customized_mods.md: documented the search architecture
  gap under Recovery Meetings — what default_qry_str contains, why
  contact_li_json is unsearchable as raw JSON, what contact_li_json_ext is
  and what needs to happen to enable contact name/email search.

Backend agent notified via ae_send_message 2026-04-08.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

documentation/CLIENT__IDAA_and_customized_mods.md

@@ -372,6 +372,21 @@ Members can filter meetings by:
 
 Search is debounced (250ms) and uses the standard Aether SWR pattern.
 
+### Search Architecture — What Is and Isn't Searched
+
+The fulltext search runs against the `default_qry_str` field (backend-computed, contains:
+`id_random`, type, name, description, timezone, recurring pattern/text, location text).
+
+**Contact names and emails are NOT currently searchable.** The `contact_li_json` field is a
+JSON longtext — MariaDB cannot efficiently substring-search it directly. The backend already
+has a `contact_li_json_ext` (STORED GENERATED, indexed) column to work around this, but it
+has not yet been added to the searchable fields whitelist in the API.
+
+**Pending fix (tracked in TODO__Agents.md, 2026-04-08):**
+- Backend: add `contact_li_json_ext` to the event object searchable fields whitelist
+- Frontend: add `contact_li_json_ext` as an OR condition in `search__event()`, and update
+  the local IDB fast-path filter to parse `contact_li_json` for instant cache results
+
 ### Edit Form — Sections and Key Fields
 
 The edit form (`ae_idaa_comp__event_obj_id_edit.svelte`) is organized into these sections.