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/Dashboard/IDashboardAuthenticator.cs

@@ -11,6 +11,7 @@ public interface IDashboardAuthenticator
     /// <param name="username">Username to authenticate.</param>
     /// <param name="password">Password to authenticate.</param>
     /// <param name="cancellationToken">Token to cancel the asynchronous operation.</param>
+    /// <returns>The authentication result.</returns>
     Task<DashboardAuthenticationResult> AuthenticateAsync(
         string? username,
         string? password,