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/FocasFactoryConfigTests.cs

@@ -119,6 +119,7 @@ public sealed class FocasFactoryConfigTests
     // ---- Driver.FOCAS-002: fixed-tree bootstrap must not declare a false ProgramInfo capability ----
 
     /// <summary>Verifies that ProgramInfo is marked unsupported when probe throws.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task FixedTree_bootstrap_marks_ProgramInfo_unsupported_when_probe_throws()
     {
@@ -146,6 +147,7 @@ public sealed class FocasFactoryConfigTests
     }
 
     /// <summary>Verifies that ProgramInfo is marked supported when probe succeeds.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task FixedTree_bootstrap_marks_ProgramInfo_supported_when_probe_succeeds()
     {