docs: complete XML doc comments via fixdocs (2757 to 131 findings)

Add missing <returns>/<param>/<summary>/<typeparam> tags and clean up
misused inheritdoc across 481 files so the documented API surface is
complete. Documentation-only (zero code lines changed). The 131 remaining
findings are inheritdoc-style warnings deliberately left to preserve
hand-written implementation rationale (plan-decision notes, race-condition
explanations).

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Tests/Runtime/GalaxyTelemetryTests.cs

@@ -31,6 +31,7 @@ public sealed class GalaxyTelemetryTests
     }
 
     /// <summary>Verifies that TracedGalaxySubscriber emits a subscribe_bulk span with tag count.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task TracedGalaxySubscriber_emits_subscribe_bulk_span_with_tag_count()
     {
@@ -52,6 +53,7 @@ public sealed class GalaxyTelemetryTests
     }
 
     /// <summary>Verifies that TracedGalaxySubscriber records error and rethrows on failure.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task TracedGalaxySubscriber_records_error_and_rethrows_on_failure()
     {
@@ -70,6 +72,7 @@ public sealed class GalaxyTelemetryTests
     }
 
     /// <summary>Verifies that TracedGalaxyDataWriter tags the secured write count.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task TracedGalaxyDataWriter_tags_secured_write_count()
     {
@@ -106,6 +109,7 @@ public sealed class GalaxyTelemetryTests
     }
 
     /// <summary>Verifies that TracedGalaxyHierarchySource tags the object count.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task TracedGalaxyHierarchySource_tags_object_count()
     {
@@ -182,7 +186,9 @@ public sealed class GalaxyTelemetryTests
 
     private sealed class FakeHierarchy : IGalaxyHierarchySource
     {
-        /// <inheritdoc />
+        /// <summary>Returns a fixed two-element hierarchy for telemetry testing.</summary>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>A task that resolves to a two-element Galaxy object list.</returns>
         public Task<IReadOnlyList<ZB.MOM.WW.MxGateway.Contracts.Proto.Galaxy.GalaxyObject>> GetHierarchyAsync(
             CancellationToken cancellationToken)
             => Task.FromResult<IReadOnlyList<ZB.MOM.WW.MxGateway.Contracts.Proto.Galaxy.GalaxyObject>>(