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.Modbus.Tests/ModbusProbeTests.cs

@@ -19,16 +19,10 @@ public sealed class ModbusProbeTests
         public volatile bool Reachable = true;
         public int ProbeCount;
 
-        /// <summary>Asynchronously connects the transport.</summary>
-        /// <param name="ct">The cancellation token.</param>
-        /// <returns>A completed task.</returns>
+        /// <inheritdoc />
         public Task ConnectAsync(CancellationToken ct) => Task.CompletedTask;
 
-        /// <summary>Asynchronously sends a Modbus PDU and returns a response.</summary>
-        /// <param name="unitId">The Modbus unit ID.</param>
-        /// <param name="pdu">The protocol data unit to send.</param>
-        /// <param name="ct">The cancellation token.</param>
-        /// <returns>A task that returns the response bytes.</returns>
+        /// <inheritdoc />
         public Task<byte[]> SendAsync(byte unitId, byte[] pdu, CancellationToken ct)
         {
             if (pdu[0] == 0x03) Interlocked.Increment(ref ProbeCount);
@@ -60,6 +54,7 @@ public sealed class ModbusProbeTests
     }
 
     /// <summary>Verifies that the initial state is Unknown before the first probe tick.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Initial_state_is_Unknown_before_first_probe_tick()
     {
@@ -73,6 +68,7 @@ public sealed class ModbusProbeTests
     }
 
     /// <summary>Verifies that the first successful probe transitions the state to Running.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task First_successful_probe_transitions_to_Running()
     {
@@ -105,6 +101,7 @@ public sealed class ModbusProbeTests
     }
 
     /// <summary>Verifies that a transport failure transitions the state to Stopped.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Transport_failure_transitions_to_Stopped()
     {
@@ -128,6 +125,7 @@ public sealed class ModbusProbeTests
     }
 
     /// <summary>Verifies that recovery transitions the state from Stopped back to Running.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Recovery_transitions_Stopped_back_to_Running()
     {
@@ -155,6 +153,7 @@ public sealed class ModbusProbeTests
     }
 
     /// <summary>Verifies that repeated successful probes do not generate duplicate Running events.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Repeated_successful_probes_do_not_generate_duplicate_Running_events()
     {
@@ -176,6 +175,7 @@ public sealed class ModbusProbeTests
     }
 
     /// <summary>Verifies that a disabled probe stays Unknown and fires no events.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Disabled_probe_stays_Unknown_and_fires_no_events()
     {
@@ -192,6 +192,7 @@ public sealed class ModbusProbeTests
     }
 
     /// <summary>Verifies that shutdown stops the probe loop.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Shutdown_stops_the_probe_loop()
     {