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.AbLegacy.Tests/AbLegacyBitIndexRangeTests.cs

@@ -68,6 +68,7 @@ public sealed class AbLegacyBitIndexRangeTests
         AbLegacyAddress.TryParse("N7:0/-1").ShouldBeNull();
 
     /// <summary>Verifies that bit in word RMW against L file uses 32-bit parent and high bit.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Bit_in_word_RMW_against_L_file_uses_32bit_parent_and_high_bit()
     {
@@ -93,6 +94,7 @@ public sealed class AbLegacyBitIndexRangeTests
     }
 
     /// <summary>Verifies that bit in word RMW high bit 15 does not corrupt via sign extension.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Bit_in_word_RMW_high_bit_15_does_not_corrupt_via_sign_extension()
     {