Seam request: Pulse inbound-message hook #2347

Problem. Inbound channel modules (modules/imessage.ts, modules/siri.ts) offer no callback point. An install that wants to observe inbound messages (for example a detection-only screen) has to edit each module.

Proposed change. Add a small emitter: each inbound module calls emitInbound({ text, channel, meta }). USER code subscribes through the S6 loader. Subscribers run detached and failures are isolated, so replies are never delayed.

Why canon benefits. One extension point serves logging, screening and analytics across every channel.