review(Driver.FOCAS.Cli): FlushLogging() in finally + fix misleading detach comment

Re-review at 7286d320. -006 (Low): FlushLogging() in all command finally blocks + tests.
-007: rewrite the inaccurate handler-detach comment (cleanup is via await using disposal).

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Cli/Commands/ReadCommand.cs

@@ -44,9 +44,19 @@ public sealed class ReadCommand : FocasCommandBase
         // already invokes ShutdownAsync, so a redundant explicit ShutdownAsync(CancellationToken.None)
         // in a finally block ran shutdown twice. The await-using on the next line is enough.
         await using var driver = new FocasDriver(options, DriverInstanceId);
-        await driver.InitializeAsync("{}", ct);
-        var snapshot = await driver.ReadAsync([tagName], ct);
-        await console.Output.WriteLineAsync(SnapshotFormatter.Format(Address, snapshot[0]));
+        try
+        {
+            await driver.InitializeAsync("{}", ct);
+            var snapshot = await driver.ReadAsync([tagName], ct);
+            await console.Output.WriteLineAsync(SnapshotFormatter.Format(Address, snapshot[0]));
+        }
+        finally
+        {
+            // Driver.FOCAS.Cli-006: flush Serilog before process exit so buffered log output
+            // emitted during driver shutdown is not silently dropped (matching DriverCommandBase
+            // docs and every sibling CLI — Modbus / AbCip / AbLegacy / TwinCAT).
+            FlushLogging();
+        }
     }
 
     /// <summary>Constructs a tag name from address and data type.</summary>