Hub: brainstorm-brief to an aro with an open session silently DISCARDS the brief body (hub.mjs:2585) — make deflect non-destructive

hub.mjs:2582-2586: when a kind=brainstorm-brief targets an aro that already has an open session, the hub sends the convener a note and RETURNS without storing body.message. The user's typed brief text is silently discarded — no DB row, not logged (cdw logs only send metadata; Caddy doesn't log bodies). Elazar lost a real brief to aro:nw at 2026-07-07T03:24:03Z; unrecoverable. Fix: make deflect NON-DESTRUCTIVE — preferred: auto-inject the brief body as a kind=brainstorm turn into the open session (what the note tells the user to do manually); fallback: echo the body back to the sender. Never drop user content on a deflect. Owner coder-llmmsgsrv-cc.