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/DriverProbeRegistrationTests.cs

@@ -32,6 +32,7 @@ public sealed class DriverProbeRegistrationTests
         "Historian.Wonderware",
     ];
 
+    /// <summary>Verifies that AddOtOpcUaDriverProbes registers a probe for every AdminUI driver type.</summary>
     [Fact]
     public void AddOtOpcUaDriverProbes_registers_a_probe_for_every_AdminUI_driver_type()
     {
@@ -49,6 +50,7 @@ public sealed class DriverProbeRegistrationTests
             byType.ContainsKey(key).ShouldBeTrue($"No IDriverProbe registered for AdminUI driver type '{key}'.");
     }
 
+    /// <summary>Verifies that AddOtOpcUaDriverProbes is idempotent when called multiple times.</summary>
     [Fact]
     public void AddOtOpcUaDriverProbes_is_idempotent()
     {