feat: show P2P diagnostics in the status pane and log

Show expandable relay, peer, and sync observations below Stats and route Diag
events to the existing Log Pane without notification or editor-status churn.
Retain departed-peer evidence and replay logs recorded before the pane opens.

Keep narrow panes usable with wrapping peer controls, readable device names,
and larger buttons. Add browser regressions for disclosure, control bounds,
button targets, and existing actions.

updates.md

@@ -16,6 +16,17 @@ Earlier releases remain available in the 1.0 release history, the 1.0 preview hi
 
 #### P2P synchronisation
 
+- P2P status shows Stats with diagnostic details collapsed by default. Expand
+  'Diagnostic log' to see the latest relay, peer, and synchronisation observations.
+  With Diag enabled, their events also appear in the Log Pane without updating
+  the editor status or producing notifications.
+    - Unobserved information is labelled explicitly. Relay rejection messages are
+      unavailable through the current transport API; an open room does not confirm
+      that a relay accepted its announcements.
+
+- Larger peer controls wrap onto additional lines in narrow panes, keeping action labels
+  readable alongside long device names.
+
 - P2P progress shows sent (↑) and received (↓) document revision counts, including
   Metadata and Chunks. Directional ⏩ labels show comparison progress even when no
   transfer is needed, and disappear three seconds after their last count change.