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.TwinCAT.Tests/TwinCATLowFindingsRegressionTests.cs

@@ -37,6 +37,7 @@ public sealed class TwinCATLowFindingsRegressionTests
     // ---- Driver.TwinCAT-006 — ResolveHost sentinel when no devices are configured ----
 
     /// <summary>Verifies that ResolveHost returns an unresolved sentinel when no devices are configured.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task ResolveHost_returns_unresolved_sentinel_when_no_devices()
     {
@@ -51,6 +52,7 @@ public sealed class TwinCATLowFindingsRegressionTests
     }
 
     /// <summary>Verifies that the unresolved sentinel does not match any GetHostStatuses entry.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task ResolveHost_unresolved_sentinel_matches_no_GetHostStatuses_entry()
     {
@@ -65,6 +67,7 @@ public sealed class TwinCATLowFindingsRegressionTests
     // ---- Driver.TwinCAT-014 — config surface knobs are honoured ----
 
     /// <summary>Verifies that ProbeOptions.Timeout is applied to probe calls.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task ProbeOptions_Timeout_is_applied_to_probe_calls()
     {
@@ -209,6 +212,7 @@ public sealed class TwinCATLowFindingsRegressionTests
     }
 
     /// <summary>Verifies that the probe loop and read operations share one client per device.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task Probe_loop_and_read_share_one_client_per_device()
     {