Search emails (v2)

Free-text email search across ALL of the authenticated user's connected mail accounts, fetched live from the providers (Google / Microsoft) — Dex stores no message content. searchQuery matches subject, body, and participants as plain text (provider search operators are neutralized); optional limit (default 25) and dateRange.{start,end} scope the window, defaulting to roughly the last 6 months. Returns { data: { email_messages, pagination } } with sender, participants, subject, snippet, and a provider deep link per message.