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/DriverTestConnectE2eTests.cs

@@ -45,6 +45,7 @@ public sealed class DriverTestConnectE2eTests
     ///     the <see cref="TestDriverConnectResult"/> reports <c>Ok = true</c> with a
     ///     sub-5 s latency. Skipped when the Docker fixture host is unreachable.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task TestConnect_Modbus_AgainstFixture_ReportsOk()
     {
@@ -74,6 +75,7 @@ public sealed class DriverTestConnectE2eTests
     ///     containing a connection-refused indicator. Skipped when the host is unreachable
     ///     (even a refused connection requires the IP to be routable).
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task TestConnect_Modbus_AgainstWrongPort_ReportsFailure()
     {
@@ -118,6 +120,7 @@ public sealed class DriverTestConnectE2eTests
     ///     <see cref="TestConnect_Modbus_AgainstFixture_ReportsOk"/> (which skips in dev).
     ///     This test does NOT require any Docker fixture and always runs.</para>
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task TestConnect_Modbus_AgainstBlackHole_ReportsTimeout()
     {