docs: backfill XML documentation across 756 files

Adds <summary>, <param>, <typeparam>, and <inheritdoc/> tags to public
members surfaced by commentchecker — resolves 5,847 of 5,869 issues
(99.6%) across three /fixdocs passes.

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests/Observability/CapabilityInvokerEnrichmentTests.cs

@@ -11,6 +11,7 @@ namespace ZB.MOM.WW.OtOpcUa.Core.Tests.Observability;
 [Trait("Category", "Integration")]
 public sealed class CapabilityInvokerEnrichmentTests
 {
+    /// <summary>Verifies that InvokerExecute logs inside call site with structured properties.</summary>
     [Fact]
     public async Task InvokerExecute_LogsInsideCallSite_CarryStructuredProperties()
     {
@@ -43,6 +44,7 @@ public sealed class CapabilityInvokerEnrichmentTests
         evt.Properties.ShouldContainKey("CorrelationId");
     }
 
+    /// <summary>Verifies that InvokerExecute does not leak context outside the call site.</summary>
     [Fact]
     public async Task InvokerExecute_DoesNotLeak_ContextOutsideCallSite()
     {
@@ -66,7 +68,10 @@ public sealed class CapabilityInvokerEnrichmentTests
 
     private sealed class InMemorySink : ILogEventSink
     {
+        /// <summary>Gets the list of captured log events.</summary>
         public List<LogEvent> Events { get; } = [];
+        /// <summary>Emits a log event by adding it to the captured events list.</summary>
+        /// <param name="logEvent">The log event to emit.</param>
         public void Emit(LogEvent logEvent) => Events.Add(logEvent);
     }
 }