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.InboundAPI/CommunicationServiceInstanceRouter.cs

@@ -12,19 +12,26 @@ public sealed class CommunicationServiceInstanceRouter : IInstanceRouter
 {
     private readonly CommunicationService _communicationService;
 
+    /// <summary>
+    /// Initializes the router with the central communication service.
+    /// </summary>
+    /// <param name="communicationService">Service used to dispatch routed calls to site clusters.</param>
     public CommunicationServiceInstanceRouter(CommunicationService communicationService)
     {
         _communicationService = communicationService;
     }
 
+    /// <inheritdoc />
     public Task<RouteToCallResponse> RouteToCallAsync(
         string siteId, RouteToCallRequest request, CancellationToken cancellationToken) =>
         _communicationService.RouteToCallAsync(siteId, request, cancellationToken);
 
+    /// <inheritdoc />
     public Task<RouteToGetAttributesResponse> RouteToGetAttributesAsync(
         string siteId, RouteToGetAttributesRequest request, CancellationToken cancellationToken) =>
         _communicationService.RouteToGetAttributesAsync(siteId, request, cancellationToken);
 
+    /// <inheritdoc />
     public Task<RouteToSetAttributesResponse> RouteToSetAttributesAsync(
         string siteId, RouteToSetAttributesRequest request, CancellationToken cancellationToken) =>
         _communicationService.RouteToSetAttributesAsync(siteId, request, cancellationToken);