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/DashboardSessionAdminResult.cs

@@ -6,6 +6,7 @@ public sealed record DashboardSessionAdminResult(
 {
     /// <summary>Creates a successful result with the given message.</summary>
     /// <param name="message">The result message.</param>
+    /// <returns>A successful <see cref="DashboardSessionAdminResult"/>.</returns>
     public static DashboardSessionAdminResult Success(string message)
     {
         return new DashboardSessionAdminResult(true, message);
@@ -13,6 +14,7 @@ public sealed record DashboardSessionAdminResult(
 
     /// <summary>Creates a failed result with the given message.</summary>
     /// <param name="message">The result message.</param>
+    /// <returns>A failed <see cref="DashboardSessionAdminResult"/>.</returns>
     public static DashboardSessionAdminResult Fail(string message)
     {
         return new DashboardSessionAdminResult(false, message);