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/Security/Tls/SelfSignedCertificateProviderTests.cs

@@ -12,6 +12,7 @@ public sealed class SelfSignedCertificateProviderTests
     private static SelfSignedCertificateProvider CreateProvider(TlsOptions options, FakeTimeProvider time)
         => new(options, NullLogger<SelfSignedCertificateProvider>.Instance, time);
 
+    /// <summary>Verifies that a generated certificate has the expected validity window, SANs (localhost, machine name, additional DNS names, loopback IPs), and the serverAuth EKU.</summary>
     [Fact]
     public void GenerateCertificate_HasExpectedSansEkuAndValidity()
     {
@@ -39,6 +40,7 @@ public sealed class SelfSignedCertificateProviderTests
             o => o.Value == "1.3.6.1.5.5.7.3.1"); // serverAuth
     }
 
+    /// <summary>Verifies that LoadOrCreate generates and persists a certificate on first call, then reuses the same persisted certificate (same thumbprint) on a subsequent call.</summary>
     [Fact]
     public void LoadOrCreate_GeneratesPersistsAndReuses_SameThumbprint()
     {
@@ -58,6 +60,7 @@ public sealed class SelfSignedCertificateProviderTests
         finally { Directory.Delete(dir, recursive: true); }
     }
 
+    /// <summary>Verifies that LoadOrCreate regenerates the certificate (a new thumbprint) once the persisted certificate's validity window has elapsed.</summary>
     [Fact]
     public void LoadOrCreate_Regenerates_WhenPersistedCertExpired()
     {
@@ -77,6 +80,7 @@ public sealed class SelfSignedCertificateProviderTests
         finally { Directory.Delete(dir, recursive: true); }
     }
 
+    /// <summary>Verifies that LoadOrCreate regenerates a valid certificate when the persisted PFX file is corrupt or unreadable.</summary>
     [Fact]
     public void LoadOrCreate_Regenerates_WhenPersistedFileCorrupt()
     {
@@ -92,6 +96,7 @@ public sealed class SelfSignedCertificateProviderTests
         finally { Directory.Delete(dir, recursive: true); }
     }
 
+    /// <summary>Verifies that LoadOrCreate throws <see cref="InvalidOperationException"/> for an expired persisted certificate when regeneration is disabled.</summary>
     [Fact]
     public void LoadOrCreate_Throws_WhenExpiredAndRegenerateDisabled()
     {
@@ -108,6 +113,7 @@ public sealed class SelfSignedCertificateProviderTests
         finally { Directory.Delete(dir, recursive: true); }
     }
 
+    /// <summary>Verifies that LoadOrCreate throws <see cref="InvalidOperationException"/> when <c>SelfSignedCertPath</c> is blank.</summary>
     [Fact]
     public void LoadOrCreate_Throws_WhenSelfSignedCertPathBlank()
     {