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/ModbusBitRmwTests.cs

@@ -14,16 +14,10 @@ public sealed class ModbusBitRmwTests
         public readonly ushort[] HoldingRegisters = new ushort[256];
         public readonly List<byte[]> Pdus = new();
 
-        /// <summary>Connects asynchronously (no-op for fake).</summary>
-        /// <param name="ct">Cancellation token (unused).</param>
-        /// <returns>A completed task.</returns>
+        /// <inheritdoc />
         public Task ConnectAsync(CancellationToken ct) => Task.CompletedTask;
 
-        /// <summary>Sends a Modbus PDU and returns a response.</summary>
-        /// <param name="unitId">The Modbus unit ID (unused).</param>
-        /// <param name="pdu">The protocol data unit to send.</param>
-        /// <param name="ct">Cancellation token (unused).</param>
-        /// <returns>A task containing the response PDU.</returns>
+        /// <inheritdoc />
         public Task<byte[]> SendAsync(byte unitId, byte[] pdu, CancellationToken ct)
         {
             Pdus.Add(pdu);
@@ -71,6 +65,7 @@ public sealed class ModbusBitRmwTests
     }
 
     /// <summary>Verifies that setting a bit reads the current register, ORs the bit, and writes back.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Bit_set_reads_current_register_ORs_bit_writes_back()
     {
@@ -90,6 +85,7 @@ public sealed class ModbusBitRmwTests
     }
 
     /// <summary>Verifies that clearing a bit reads the current register, ANDs the bit off, and writes back.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Bit_clear_reads_current_register_ANDs_bit_off_writes_back()
     {
@@ -104,6 +100,7 @@ public sealed class ModbusBitRmwTests
     }
 
     /// <summary>Verifies that concurrent bit writes to the same register preserve all updates via serialization.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Concurrent_bit_writes_to_same_register_preserve_all_updates()
     {
@@ -123,6 +120,7 @@ public sealed class ModbusBitRmwTests
     }
 
     /// <summary>Verifies that bit writes to different registers proceed in parallel without contention.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Bit_write_on_different_registers_proceeds_in_parallel_without_contention()
     {
@@ -140,6 +138,7 @@ public sealed class ModbusBitRmwTests
     }
 
     /// <summary>Verifies that bit writes preserve other bits in the same register.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Bit_write_preserves_other_bits_in_the_same_register()
     {