docs: what a person checks before 0.2.6.6 goes to stable, and the file it is

Six boxes on the laptop: the reboot that waits for an idle, silent
computer, and the television switched on after the computer. The exact
file and its sha256, so that promotion names the bytes canary ran.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/testing.md

@@ -3,6 +3,36 @@
 Run against the exact artifact published to canary, on the real endpoint,
 before promoting to stable with `./update_stable.sh`.
 
+## Before 0.2.6.6 goes to stable
+
+The container gate and the lab passed both of these. Neither can prove
+them on real hardware, so a person does, on the prayer-room laptop, which
+takes 0.2.6.6 from canary. If every box is ticked, 0.2.6.6 is promoted
+**as the same file**, never rebuilt:
+
+```
+ekklesia-classroom_0.2.6.6_amd64.deb
+sha256 2b972391974265ba220c58ae0a8f287664a42228f062278956b89017bd5a54f7
+./update_stable.sh 0.2.6.6 2b972391974265ba220c58ae0a8f287664a42228f062278956b89017bd5a54f7
+```
+
+**Waiting to reboot (since 0.2.6.5)** — details under [OTA](#ota):
+
+- [ ] Using the computer after an update has installed: it does not restart
+- [ ] A video playing with sound, mouse left alone: it does not restart
+- [ ] Left untouched and silent, it restarts about 30 minutes later, on
+      the new version
+- [ ] Switched off before that restart: it starts normally next time, on
+      the new version, and does not restart again
+
+**The television arriving late (0.2.6.6)** — details under
+[the television switched on after a night-time reboot](#the-television-switched-on-after-a-night-time-reboot):
+
+- [ ] Rebooted with the television off at the set (if the room allows it),
+      then switched on: the classroom's landscape, not Plasma's purple
+- [ ] The panel is the room's own: same launchers, same order, clock bottom
+      right
+
 ## Boot
 
 - [ ] Cold boot reaches the classroom shell with no terminal or window junk