docs: backfill XML documentation across 756 files

Adds <summary>, <param>, <typeparam>, and <inheritdoc/> tags to public
members surfaced by commentchecker — resolves 5,847 of 5,869 issues
(99.6%) across three /fixdocs passes.

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Tests/Runtime/MxAccessSeverityMapperTests.cs

@@ -13,6 +13,10 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Tests.Runtime;
 /// </summary>
 public sealed class MxAccessSeverityMapperTests
 {
+    /// <summary>Verifies that Map assigns the expected severity bucket and OPC UA severity value.</summary>
+    /// <param name="rawMxAccessSeverity">The raw MxAccess severity integer to map.</param>
+    /// <param name="expectedBucket">The expected AlarmSeverity bucket.</param>
+    /// <param name="expectedOpcUaSeverity">The expected OPC UA numeric severity value.</param>
     [Theory]
     [InlineData(0, AlarmSeverity.Low, MxAccessSeverityMapper.OpcUaSeverityLow)]
     [InlineData(1, AlarmSeverity.Low, MxAccessSeverityMapper.OpcUaSeverityLow)]
@@ -32,6 +36,7 @@ public sealed class MxAccessSeverityMapperTests
         opcUa.ShouldBe(expectedOpcUaSeverity);
     }
 
+    /// <summary>Verifies that Map clamps negative severities into the low bucket.</summary>
     [Fact]
     public void Map_clamps_negative_severities_into_low_bucket()
     {