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/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/LdapOptionsBindingTests.cs

@@ -88,6 +88,8 @@ public sealed class ProdOverlayValidationTests
         return configuration.GetSection(LdapOptions.SectionName).Get<LdapOptions>() ?? new LdapOptions();
     }
 
+    /// <summary>Verifies that each production overlay declares the ldaps transport.</summary>
+    /// <param name="fileName">The overlay file name to validate.</param>
     [Theory]
     [InlineData("appsettings.admin.json")]
     [InlineData("appsettings.driver.json")]
@@ -100,6 +102,8 @@ public sealed class ProdOverlayValidationTests
         options.Transport.ShouldBe(LdapTransport.Ldaps);
     }
 
+    /// <summary>Verifies that each production overlay passes startup validation.</summary>
+    /// <param name="fileName">The overlay file name to validate.</param>
     [Theory]
     [InlineData("appsettings.admin.json")]
     [InlineData("appsettings.driver.json")]
@@ -114,6 +118,7 @@ public sealed class ProdOverlayValidationTests
         Sut.Validate(null, options).Succeeded.ShouldBeTrue();
     }
 
+    /// <summary>Verifies that the Development overlay passes startup validation via the DevStub exemption.</summary>
     [Fact]
     public void Development_overlay_passes_startup_validation_via_devstub_exemption()
     {