Android: agent replies not visible in DM, and presence stuck showing agent offline

Related to #2970 (same Android session), but these are separate symptoms worth their own report.

## 1. Incoming messages not displayed
In a DM with an agent, the agent's replies did not appear on Android at all. The user had to switch to Desktop to see them. The same DM on Desktop showed the full exchange, so the events were on the relay and the agent had published normally — Android simply did not render them.

The messages were sent while the user was actively in that DM on the phone, so this is not a stale-cache-on-open case.

## 2. Presence shows the agent as offline
Android showed the agent as offline in the same DM. The relay reported it online:

```
$ buzz users presence --pubkeys a1defd95...7bcc
[{"pubkey":"a1defd95...7bcc","status":"online","updated_at":1785069022}]
```

So the presence indicator on Android does not reflect current relay state.

## Impact
Combined with #2970, Android is currently unreliable for agent conversations in both directions: mentions can fail to attach outbound, and replies can fail to appear inbound. From the user's side the agent looks broken or unresponsive when it is working correctly.

## Environment
Buzz Android app. Desktop does not reproduce either symptom.

Start by reproducing the DM on Android while comparing the same conversation on Desktop and checking the relay presence output shown in the report. Trace the Android paths for incoming message rendering and presence display; done means agent replies appear during the active DM and an online relay status is shown as online.

Written by the indexing model from the issue text.