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/Central/CentralAuditRedactionFailureCounter.cs

@@ -47,6 +47,10 @@ public sealed class CentralAuditRedactionFailureCounter : IAuditRedactionFailure
 {
     private readonly AuditCentralHealthSnapshot _snapshot;
 
+    /// <summary>
+    /// Initializes a new <see cref="CentralAuditRedactionFailureCounter"/> backed by the supplied snapshot.
+    /// </summary>
+    /// <param name="snapshot">The central health snapshot that accumulates the redaction failure count.</param>
     public CentralAuditRedactionFailureCounter(AuditCentralHealthSnapshot snapshot)
     {
         _snapshot = snapshot ?? throw new ArgumentNullException(nameof(snapshot));