docs: describe hardware approval gateway

deploy/server/README.md

@@ -59,9 +59,17 @@ The workstation service must use the same `.env.auth` as the public container;
 the SSH key must be restricted to that single reverse-listen port and must not
 be allowed to run remote commands.
 
-The physical bench is a process-wide single-flight resource. A hardware action
+Public physical execution uses a local-approval lease. A browser first submits
-owns the bench from intent planning through final physical feedback. Concurrent
+an access request, and the bench operator chooses one terminal at
-hardware actions and passive physical-state reads receive HTTP `409`
+`http://127.0.0.1:8000/hardware-control`. The decision API is restricted to
-(`hardware_busy`) with `Retry-After`; they never enter the CAN path or wait to run
+unproxied loopback traffic, so it cannot be used through the public domain or
-later against stale position state. Dry-run and simulated-hardware requests are
+the SSH tunnel. The approved terminal may run multiple tests; its lease is
-not serialized by this gate.
+revoked after 180 seconds without a physical test, on voluntary release, or by
+the local operator. A process restart clears all leases and pending requests.
+
+Inside the approved lease, the physical bench remains a process-wide
+single-flight resource. A hardware action owns the bench from intent planning
+through final physical feedback. Concurrent actions and passive physical-state
+reads receive HTTP `409` (`hardware_busy`) with `Retry-After`; they never enter
+the CAN path or wait to run later against stale position state. Dry-run and
+simulated-hardware requests are not serialized by this action-level gate.