docs(tst-05): revisit under the restored windev tier — scheduled half closed, control-command coverage still open

The nightly-windev job (cycle-2 TST-25) discharges TST-05's scheduling design:
cron 0 6 * * * runs run-windev-ci.sh live, which sets
MXGATEWAY_RUN_LIVE_MXACCESS_TESTS=1, runs WorkerLiveMxAccessSmokeTests on windev,
and opens a Gitea issue on failure. That converts 'run by memory' into 'runs
nightly, reports failures'.

The finding's other half — audit the live suite for coverage of each of the eleven
late-added command kinds — is not discharged. The audit's answer is negative for
five: the suite covers all six COM commands and none of the five control commands
(Ping/GetSessionState/GetWorkerInfo/DrainEvents/ShutdownWorker), which are exactly
the kinds the finding calls masked by FakeWorkerHarness canned replies. Recorded as
Partially done with the residual test work specified, rather than claiming closure.

docs/GatewayTesting.md

@@ -82,7 +82,17 @@ fake-worker tests cannot validate:
   when the rig does not drive sample-bearing buffered batches on demand.
 
 All eight tests are gated by the same `MXGATEWAY_RUN_LIVE_MXACCESS_TESTS=1`
-opt-in variable.
+opt-in variable. Opt-in does not mean unscheduled: the `nightly-windev` job runs
+this suite on windev every night at 06:00 UTC and files a Gitea issue when it goes
+red (see [Continuous Integration](#continuous-integration)), so the smoke no longer
+depends on someone remembering to set the variable.
+
+Known coverage gap: the suite reaches all six late-added MXAccess **COM** commands
+but none of the five **control** commands (`Ping`, `GetSessionState`,
+`GetWorkerInfo`, `DrainEvents`, `ShutdownWorker`). Those are implemented off-STA in
+`Worker/Ipc/WorkerPipeSession.cs` and are asserted only against
+`FakeWorkerHarness`'s canned replies, so no test proves the *real* worker answers
+them. Closing that is the residual half of archreview TST-05.
 
 Build the worker before running the smoke: