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.AbCip.Tests/AbCipDriverWriteTests.cs

@@ -21,6 +21,7 @@ public sealed class AbCipDriverWriteTests
     }
 
     /// <summary>Verifies that unknown reference maps to BadNodeIdUnknown status.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Unknown_reference_maps_to_BadNodeIdUnknown()
     {
@@ -34,6 +35,7 @@ public sealed class AbCipDriverWriteTests
     }
 
     /// <summary>Verifies that non-writable tags map to BadNotWritable status.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Non_writable_tag_maps_to_BadNotWritable()
     {
@@ -48,6 +50,7 @@ public sealed class AbCipDriverWriteTests
     }
 
     /// <summary>Verifies that successful DInt writes encode and flush values.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Successful_DInt_write_encodes_and_flushes()
     {
@@ -64,6 +67,7 @@ public sealed class AbCipDriverWriteTests
     }
 
     /// <summary>Verifies that bit-in-DInt writes succeed via read-modify-write.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Bit_in_dint_write_now_succeeds_via_RMW()
     {
@@ -85,6 +89,7 @@ public sealed class AbCipDriverWriteTests
     }
 
     /// <summary>Verifies that non-zero libplctag status after write maps correctly.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Non_zero_libplctag_status_after_write_maps_via_AbCipStatusMapper()
     {
@@ -100,6 +105,7 @@ public sealed class AbCipDriverWriteTests
     }
 
     /// <summary>Verifies that type mismatch surfaces BadTypeMismatch status.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Type_mismatch_surfaces_BadTypeMismatch()
     {
@@ -126,6 +132,7 @@ public sealed class AbCipDriverWriteTests
     }
 
     /// <summary>Verifies that overflow surfaces BadOutOfRange status.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Overflow_surfaces_BadOutOfRange()
     {
@@ -144,6 +151,7 @@ public sealed class AbCipDriverWriteTests
     }
 
     /// <summary>Verifies that exceptions during write surface BadCommunicationError.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Exception_during_write_surfaces_BadCommunicationError()
     {
@@ -160,6 +168,7 @@ public sealed class AbCipDriverWriteTests
     }
 
     /// <summary>Verifies that batch write preserves order across success and failure.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Batch_preserves_order_across_success_and_failure()
     {
@@ -192,6 +201,7 @@ public sealed class AbCipDriverWriteTests
     }
 
     /// <summary>Verifies that cancellation propagates from write operations.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Cancellation_propagates_from_write()
     {