forgetest: the machine's print behavior under the offline service

Four cloud tests no longer need the app, an account, a network, or
anything on the bed: cloud.lid-interlock-abort, lid-during-button-wait,
paused-lid-cancel and oversize-stream run under the offline service
(enter_offline restarts the cloud client with the /run marker for that
one start; Offline is the socket; offline_job writes the job). The jobs
come from forgetest/puls.py: the header of a factory print of this
machine type (134 tags, MCsn 0, so the client's limits and settings come
from where a service job's do) over a square traced at a steady feed
with a leading power byte of zero and no LASER bit anywhere - the arm
unlocks the latch, the beam is never commanded, so the tests stay live
and need no scrap. A job longer than the ring (33 MiB of ticks, an hour
of squares) is an 87 kB gzip written in a tenth of a second, in place of
a full-bed raster designed in the app.

session_live reads the offline mark as "no web session"; enter_cloud
restarts an offline client with the service, so cloud.pause-resume (the
one real print left, with cloud.mode-switch the service-protocol half of
the catalog) follows the offline tests without the operator's hand.
Replays over a fake socket; the contract and BRINGUP say how the cloud
catalog splits. Catalog consequence: the four re-ported tests move;
nothing else is invalidated.

docs/ACCEPTANCE.md

@@ -149,6 +149,21 @@ bench, or one whose `/data` has been wiped, starts from a full campaign.
    it carries the two service-driven motions with it: the connect-time
    hunt run with the lid open, and the web-service homing (`$H` with
    `homing_mode = gfcloud`) after the switch back.
+   The cloud tests split by what they prove. The service protocol (sign-in,
+   the WebSocket, the hunt, the print from the app, progress, the job's
+   limits reaching the engine) is `cloud.mode-switch` and one real print,
+   `cloud.pause-resume`. The machine's print behavior (the lid and
+   interlock aborts, the button-wait cancel, a paused print ended by the
+   lid, a print longer than the ring with the app's cancel) runs under the
+   **offline service** (`enter_offline`: the cloud client restarted with
+   the `/run/gfcloud-offline` marker, no account, no network; the test
+   hands it a synthesized job over `/run/gfcloud-offline.sock` and reads
+   the machine's events back, see `forgetest/puls.py` and the cloud
+   client's `docs/CLOUD.md`). Those jobs carry no laser command, so
+   nothing is on the bed and nothing burns, but the arm still unlocks the
+   latch, so they stay `live`. The offline client is left running; the
+   next test that needs the service restarts it (`enter_cloud` does), as
+   does a mode switch or a controller restart.
 4. Or hand the whole list to a queue. **Run what is left** offers two:
    **Unattended** takes every `auto` test the campaign does not already
    count as satisfied, and needs nobody in the room; **Operator and live**