PMP messages are grouped together

[Sugaryyyy]

Describe the bug

messages are grouped by user and not PMP, which hides the PMP if no one else sent a message

Reproduction

1. send message
2. switch to a different PMP
3. send another message

Expected behavior

message grouping based on PMPs, so when you switch PMPs it's clear who sent what

Platform and versions

Sable: v1.10.2-dev (b91d18d)
OS: Android
Browser: Vanadium 
HS: tuwunel

Additional context

No response