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.FOCAS.Tests/FocasPmcBitRmwTests.cs

@@ -66,6 +66,7 @@ public sealed class FocasPmcBitRmwTests
     }
 
     /// <summary>Verifies that a bit set operation surfaces as Good status and flips the bit.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Bit_set_surfaces_as_Good_status_and_flips_bit()
     {
@@ -81,6 +82,7 @@ public sealed class FocasPmcBitRmwTests
     }
 
     /// <summary>Verifies that clearing a bit preserves other bits.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Bit_clear_preserves_other_bits()
     {
@@ -95,6 +97,7 @@ public sealed class FocasPmcBitRmwTests
     }
 
     /// <summary>Verifies that subsequent bit sets in the same byte compose correctly.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Subsequent_bit_sets_in_same_byte_compose_correctly()
     {
@@ -112,6 +115,7 @@ public sealed class FocasPmcBitRmwTests
     }
 
     /// <summary>Verifies that bit writes to different bytes do not contend.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Bit_write_to_different_bytes_does_not_contend()
     {