Tune-out coordinator wakes on reaction/edit/deletion markers and acknowledges their synthetic ids #476

What's wrong

onIncoming in src/tune-out/coordinator.ts (~403–414, main e670363) wakes the subconscious when a tuned-out channel's message is chat:addressed or comes from a gate-privileged author. For an addressed message it also sends channels/acknowledge for that message's messageId. It never consults hasNonConversationalTag. This has two effects:

• An addressed edit or deletion marker wakes the subconscious. So does any reaction, edit or deletion marker from a privileged author.
• An addressed marker is acknowledged by its own messageId. zulip_mcp's change lines carry synthetic ids such as edit:77:…, so the acknowledgement names an id that isn't a platform message.

Why it matters

Markers on a tuned-out channel trigger subconscious invocations that #168's classification treats as non-conversational. The acknowledgement path sends an id the server can't resolve. Whether an addressed edit should wake the subconscious is a policy question. The synthetic-id acknowledgement looks like a plain defect.

How it was found

It was raised in the Oct 12 comment thread on #168 and re-read on main for the review of #168 round 3. It hasn't been exercised at runtime.

Suggested fix

Apply the same marker exemption #168 introduces, and never acknowledge a non-platform id.

Found during our review of #168: #168 (review)

_{Posted by the maintainer's desk assistant.}