feat: authenticate Windows command launcher and signal helper

docs/testing.md

@@ -61,9 +61,16 @@ that command text is accepted once, output is journaled, lifecycle/terminal
 events are durable, and a script cannot launch before its contiguous upload is
 committed. The Windows build uses the same executor contract with the
 platform-native adapter: a verified token is selected, the child is created
-suspended, assigned to a kill-on-close Job, and only then released. The
-durable `launch_phase` barrier is recovered as `interrupted` after a daemon
-restart, so an uncertain release is never redispatched.
+suspended, assigned to a kill-on-close Job, and held behind an authenticated
+per-command launcher pipe. The daemon records `launch_prepared`, then the
+durable `launch_authorized` transition sends the launcher's release frame; the
+launcher resumes the shell only after that acknowledgement. The durable
+`launch_phase` barrier is recovered as `interrupted` after a daemon restart, so
+an uncertain release is never redispatched.
+
+The Windows artifact is linked with the GUI subsystem (`-H=windowsgui`) so
+service, launcher, and tray startup do not flash a console. Human-facing modes
+still attach to a parent console explicitly when one exists.
 
 Suite output is capped at 1 MiB and stored as `artifacts/suite.log`. A failed
 run remains inspectable and can be moved back to `ready` with `recover`, then