fix: clarify the P2P diagnostic summary label

Call the three latest category observations 'Diagnostic summary' and retain
'Open log' for their event history. Update the primary English message,
status card, and release note together.

Validated with the refactored Commonlib candidate: full checks, 2,063 unit
tests with one skipped, production build, iOS 15 compatibility, and five
Chromium cases. Dependency declarations remain on the published version
until the immutable Commonlib update is available.

src/features/P2PSync/P2PReplicator/P2PServerStatusCard.svelte

@@ -203,7 +203,7 @@
                 </div>
             </div>
             <details class="diag-details">
-                <summary>{translateMessage("Diagnostic log")}</summary>
+                <summary>{translateMessage("Diagnostic summary")}</summary>
                 <div class="diag-summary">
                     {#each diagnosticRows as row (row.category)}
                         <div title={row.title}>