Both real mobile clients (iOS, Android) forward messages via POST
/v1/im/messages/forward, never a client-side {pub} packet -- confirmed
by reading their source directly. Switches web's single-message and
bulk forward paths to the same endpoint, which copies message content
verbatim regardless of shape, eliminating the client-side flat-content
detection this used to require. Comment-sending stays on the existing
sendText() path, unchanged, to preserve current ordering.
Removes send.ts's now-unused forwardMessage/flatForwardPayload.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>