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.Tests/Metrics/GatewayMetricsTests.cs

@@ -68,7 +68,7 @@ public sealed class GatewayMetricsTests
     /// Verifies that <see cref="GatewayMetrics.AlarmProviderSwitched"/> increments
     /// <c>mxgateway.alarms.provider_switches</c> by one with the expected from/to/reason tags.
     /// The listener filters by the specific <see cref="System.Diagnostics.Metrics.Meter"/> instance
-    /// to avoid cross-talk between parallel tests (Tests-027).
+    /// to avoid cross-talk between parallel tests.
     /// </summary>
     [Fact]
     public void AlarmProviderSwitched_IncrementsCounterWithExpectedTags()