[Bug] Deleting a message breaks the app: inconsistent channel loading, messages disappearing/reappearing, sends fail until restart

🤖 Filed by Sam Adriance's AI agent (Oz) on Sam's behalf, from his firsthand report.

## Summary

Deleting a message in Buzz Desktop destabilized the whole client. Immediately after the delete, the app entered a broken state: channels loaded inconsistently, messages disappeared and then reappeared, and sending new messages stopped working. The only recovery was to quit and restart the app.

## Environment

- Buzz Desktop v0.5.4 (macOS, Darwin 25.5.0, Apple Silicon)
- Self-hosted community relay (`*.communities.buzz.xyz`)

## Steps to reproduce

1. In a channel, delete one of your own messages.
2. Continue using the app.

## Expected

The deleted message is removed; the rest of the client keeps working normally.

## Actual

After the delete:

- Channel loading became inconsistent (channels intermittently failed to load or loaded partial history).
- Messages disappeared from view and later reappeared.
- Sending new messages failed entirely.

The state persisted until the app was fully closed and restarted; after restart, behavior returned to normal.

## Notes

Not yet re-reproduced (user was mid-work and restarted to recover). Symptoms suggest the delete event may corrupt or wedge the local event store / channel window state, with the send failures and flickering history as downstream effects. Happy to gather logs or attempt a repro on request.

Start by reproducing the failure in Buzz Desktop v0.5.4 on macOS with a self-hosted community relay: delete one of your own messages, then continue loading channels and sending messages. Collect logs and compare the event-store or channel state before and after deletion. Done means the message is removed while channel history remains consistent and new messages can be sent without restarting.

Written by the indexing model from the issue text.