docs+ui: backfill XML doc comments and finish dashboard layout pass

Adds missing <summary>/<param> XML docs across 99 server, worker, and test
files so CommentChecker reports zero issues (TreatWarningsAsErrors needs the
analyzer clean). Bundles in WIP dashboard work: NavSection extraction,
MainLayout/site.css/js styling alignment, and DashboardOptions/Auth tweaks.

src/ZB.MOM.WW.MxGateway.Tests/Gateway/Sessions/SessionManagerTests.cs

@@ -50,6 +50,7 @@ public sealed class SessionManagerTests
         Assert.Equal(clock.GetUtcNow() + TimeSpan.FromMinutes(30), session.LeaseExpiresAt);
     }
 
+    /// <summary>Verifies that session generation creates client correlation ID from client name and session ID.</summary>
     [Fact]
     public async Task OpenSessionAsync_GeneratesClientCorrelationIdFromClientNameAndSessionId()
     {
@@ -124,6 +125,7 @@ public sealed class SessionManagerTests
         Assert.True(session.LeaseExpiresAt > DateTimeOffset.UtcNow);
     }
 
+    /// <summary>Verifies that gateway session subscribe bulk forwards one bulk command and returns results.</summary>
     [Fact]
     public async Task GatewaySessionSubscribeBulkAsync_ForwardsOneBulkCommandAndReturnsResults()
     {
@@ -168,6 +170,7 @@ public sealed class SessionManagerTests
         Assert.Equal(["Galaxy.Tag.Value"], workerClient.LastCommand?.Command.SubscribeBulk.TagAddresses);
     }
 
+    /// <summary>Verifies that gateway session write bulk forwards one bulk command and returns results.</summary>
     [Fact]
     public async Task GatewaySessionWriteBulkAsync_ForwardsOneBulkCommandAndReturnsResults()
     {
@@ -232,6 +235,7 @@ public sealed class SessionManagerTests
         Assert.Equal(2, workerClient.LastCommand?.Command.WriteBulk.Entries.Count);
     }
 
+    /// <summary>Verifies that gateway session read bulk forwards one bulk command and returns results.</summary>
     [Fact]
     public async Task GatewaySessionReadBulkAsync_ForwardsOneBulkCommandAndReturnsResults()
     {
@@ -497,6 +501,7 @@ public sealed class SessionManagerTests
     /// <see cref="ArgumentException.ThrowIfNullOrWhiteSpace"/>. A blank or whitespace reason must throw
     /// <see cref="ArgumentException"/> before any session lookup or worker call runs.
     /// </summary>
+    /// <param name="blankReason">A blank or whitespace reason string.</param>
     [Theory]
     [InlineData("")]
     [InlineData(" ")]
@@ -710,6 +715,7 @@ public sealed class SessionManagerTests
         Assert.Equal(0, workerClient.ShutdownCount);
     }
 
+    /// <summary>Verifies that shutdown closes all registered sessions.</summary>
     [Fact]
     public async Task ShutdownAsync_ClosesAllRegisteredSessions()
     {