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/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/OpcUa/OpcUaPublishActorTests.cs

@@ -160,36 +160,21 @@ public sealed class OpcUaPublishActorTests : RuntimeActorTestBase
         public List<(string AlarmNodeId, bool Active, bool Acknowledged, DateTime Ts)> Alarms =>
             AlarmQueue.ToList();
 
-        /// <summary>Records a value update.</summary>
-        /// <param name="nodeId">The OPC UA node identifier.</param>
-        /// <param name="value">The attribute value.</param>
-        /// <param name="quality">The OPC UA quality code.</param>
-        /// <param name="ts">The timestamp of the update.</param>
+        /// <inheritdoc />
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime ts) =>
             ValueQueue.Enqueue((nodeId, value, quality, ts));
 
-        /// <summary>Records an alarm state update.</summary>
-        /// <param name="alarmNodeId">The OPC UA alarm node identifier.</param>
-        /// <param name="active">Whether the alarm is active.</param>
-        /// <param name="acknowledged">Whether the alarm is acknowledged.</param>
-        /// <param name="ts">The timestamp of the update.</param>
+        /// <inheritdoc />
         public void WriteAlarmState(string alarmNodeId, bool active, bool acknowledged, DateTime ts) =>
             AlarmQueue.Enqueue((alarmNodeId, active, acknowledged, ts));
 
-        /// <summary>Ensures a folder exists (no-op in test).</summary>
-        /// <param name="folderNodeId">The OPC UA folder node identifier.</param>
-        /// <param name="parentNodeId">The parent folder node identifier, or null for root.</param>
-        /// <param name="displayName">The display name of the folder.</param>
+        /// <inheritdoc />
         public void EnsureFolder(string folderNodeId, string? parentNodeId, string displayName) { }
 
-        /// <summary>Ensures a variable exists (no-op in test).</summary>
-        /// <param name="variableNodeId">The OPC UA variable node identifier.</param>
-        /// <param name="parentFolderNodeId">The parent folder node identifier, or null for root.</param>
-        /// <param name="displayName">The display name of the variable.</param>
-        /// <param name="dataType">The OPC UA built-in type name.</param>
+        /// <inheritdoc />
         public void EnsureVariable(string variableNodeId, string? parentFolderNodeId, string displayName, string dataType) { }
 
-        /// <summary>Records a rebuild call.</summary>
+        /// <inheritdoc />
         public void RebuildAddressSpace() => Interlocked.Increment(ref RebuildCalls);
     }
 
@@ -199,8 +184,7 @@ public sealed class OpcUaPublishActorTests : RuntimeActorTestBase
         private readonly ConcurrentQueue<byte> _q = new();
         /// <summary>Gets the recorded service levels.</summary>
         public byte[] Levels => _q.ToArray();
-        /// <summary>Records a service level publish.</summary>
-        /// <param name="serviceLevel">The service level value to publish.</param>
+        /// <inheritdoc />
         public void Publish(byte serviceLevel) => _q.Enqueue(serviceLevel);
     }
 }

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/OpcUa/ServiceLevelEndToEndTests.cs

@@ -25,6 +25,7 @@ public sealed class ServiceLevelEndToEndTests : RuntimeActorTestBase
     private static CancellationToken Ct => CancellationToken.None;
 
     /// <summary>Verifies that the primary cluster leader sets Server ServiceLevel to 240.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Primary_leader_drives_Server_ServiceLevel_to_240()
     {
@@ -65,6 +66,7 @@ public sealed class ServiceLevelEndToEndTests : RuntimeActorTestBase
     }
 
     /// <summary>Verifies that the secondary node sets Server ServiceLevel to 100.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Secondary_drives_Server_ServiceLevel_to_100()
     {