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.SiteEventLogging/EventLogQueryService.cs

@@ -17,6 +17,10 @@ public class EventLogQueryService : IEventLogQueryService
     private readonly SiteEventLogOptions _options;
     private readonly ILogger<EventLogQueryService> _logger;
 
+    /// <summary>Initializes a new instance of <see cref="EventLogQueryService"/>.</summary>
+    /// <param name="eventLogger">The concrete event logger providing lock-guarded database access.</param>
+    /// <param name="options">Site event log options (page size and other query settings).</param>
+    /// <param name="logger">Logger instance.</param>
     public EventLogQueryService(
         SiteEventLogger eventLogger,
         IOptions<SiteEventLogOptions> options,
@@ -43,6 +47,7 @@ public class EventLogQueryService : IEventLogQueryService
             .Replace("_", "\\_");
     }
 
+    /// <inheritdoc />
     public EventLogQueryResponse ExecuteQuery(EventLogQueryRequest request)
     {
         try