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.AdminUI.Tests/HistorianWonderwareDriverPageFormSerializationTests.cs

@@ -15,6 +15,7 @@ public sealed class HistorianWonderwareDriverPageFormSerializationTests
         WriteIndented = false,
     };
 
+    /// <summary>Verifies that a round-trip serialization/deserialization preserves all known fields.</summary>
     [Fact]
     public void RoundTrip_PreservesKnownFields()
     {
@@ -42,6 +43,7 @@ public sealed class HistorianWonderwareDriverPageFormSerializationTests
         back.ProbeTimeoutSeconds.ShouldBe(25);
     }
 
+    /// <summary>Verifies that null timeout values fall back to the expected defaults after deserialization.</summary>
     [Fact]
     public void RoundTrip_NullTimeouts_UsesDefaults()
     {
@@ -59,6 +61,7 @@ public sealed class HistorianWonderwareDriverPageFormSerializationTests
         back.EffectiveCallTimeout.ShouldBe(TimeSpan.FromSeconds(30));
     }
 
+    /// <summary>Verifies that unknown JSON properties are silently ignored during deserialization.</summary>
     [Fact]
     public void Deserialize_DropsUnknownFields()
     {
@@ -82,6 +85,7 @@ public sealed class HistorianWonderwareDriverPageFormSerializationTests
         back.PipeName.ShouldBe("otopcua-historian");
     }
 
+    /// <summary>Verifies that the form model FromRecord/ToRecord round-trip preserves all fields losslessly.</summary>
     [Fact]
     public void FormModel_RoundTrip_PreservesAllFields()
     {