docs: add XML doc comments across src + Sister Projects section in CLAUDE.md

Bulk CommentChecker pass: fills in <param>/<inheritdoc> tags on public
APIs across all 23 src/ projects so the doc-coverage gate is green. Also
adds a Sister Projects section to CLAUDE.md pointing at the MxAccess
Gateway and OtOpcUa sibling repos, and gitignores local credential
captures (*login*.txt) and the wonder-app-vd03 deploy/ artifacts.

src/ScadaLink.AuditLog/Site/SiteAuditBacklogReporter.cs

@@ -52,6 +52,11 @@ public sealed class SiteAuditBacklogReporter : IHostedService, IDisposable
     private CancellationTokenSource? _cts;
     private Task? _loop;
 
+    /// <summary>Initializes a new instance of <see cref="SiteAuditBacklogReporter"/>.</summary>
+    /// <param name="queue">The site audit queue used to probe the backlog count.</param>
+    /// <param name="collector">The site health collector that receives the backlog snapshot.</param>
+    /// <param name="logger">Logger instance.</param>
+    /// <param name="refreshInterval">Poll interval override; defaults to <see cref="DefaultRefreshInterval"/> (30 s).</param>
     public SiteAuditBacklogReporter(
         ISiteAuditQueue queue,
         ISiteHealthCollector collector,