[bug] Chat history partially lost after reconnection or app restart

[Catrya]

Chat messages disappear partially after certain connectivity or lifecycle events. Two confirmed patterns:

1. After internet loss + reconnect: When the app lost internet mid-session and reconnected, only the most recent part of the chat was visible after refreshing. Older messages were gone.
2. After 24h without opening the app: On the following day, only the beginning of the chat was visible — recent messages had disappeared.

In both cases, using the shared key on Mostrix shows the complete chat, confirming the messages exist on the relay and the issue is client-side only.

To reproduce
Pattern 1:

1. Open an active trade chat
2. Lose internet mid-session (airplane mode or disconnect)
3. Reconnect and refresh the chat
4. Expected: full chat history. Actual: only tail of conversation visible

Pattern 2:

1. Have an active trade chat with messages
2. Close the app for ~24h
3. Reopen the app and navigate to the chat
4. Expected: full history. Actual: only the beginning of the conversation visible

Additional context
The shared key works correctly in Mostrix, confirming the data is on the relay. The bug is in how the app loads or preserves messages locally.