docs(src): add missing XML docs and strip tracking-ID comments

Sweep of 203 source files resolving CommentChecker findings: add
<summary>/<param>/<returns>/<inheritdoc> where missing, and remove
resolved task/issue tracking markers (Tests-NNN, Worker-NNN, Server-NNN,
Task N) from code comments. Comment/doc-only — no logic changes.
Server+Tests build clean under TreatWarningsAsErrors.

src/ZB.MOM.WW.MxGateway.Server/Security/Audit/SqliteCanonicalAuditStore.cs

@@ -43,6 +43,7 @@ public sealed class SqliteCanonicalAuditStore(AuthSqliteConnectionFactory connec
     /// <summary>Inserts a canonical audit event into the <c>audit_event</c> table.</summary>
     /// <param name="auditEvent">The canonical event to persist.</param>
     /// <param name="cancellationToken">Token to observe for cancellation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task InsertAsync(AuditEvent auditEvent, CancellationToken cancellationToken)
     {
         ArgumentNullException.ThrowIfNull(auditEvent);
@@ -79,6 +80,7 @@ public sealed class SqliteCanonicalAuditStore(AuthSqliteConnectionFactory connec
     /// <summary>Returns the most recent canonical audit events, newest first.</summary>
     /// <param name="limit">Maximum number of events to return.</param>
     /// <param name="cancellationToken">Token to observe for cancellation.</param>
+    /// <returns>The most recent audit events, up to <paramref name="limit"/>, newest first.</returns>
     public async Task<IReadOnlyList<AuditEvent>> ListRecentAsync(int limit, CancellationToken cancellationToken)
     {
         if (limit <= 0)