docs: temporary workspace restore, the admin link bubble, and Sunday's checks

wonder-ink.md: where WonderInk keeps its sign-in (Basic auth in a cookie)
and why only tabs are restored; what comes back and what never does; what
counts as use; when it is not restored; the test-only override. And the
link bubble teachers saw: WonderInk's CKEditor 5 for Admin accounts,
where a plain click on a link is an editing click by design; Viewers get
one-click links, measured on the real Saul lesson, and Wonder Ink does
not override the editor.

The manual says closing still signs you out and recent tabs come back
for two hours. testing.md has the Little Waders checklist.

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

docs/backlog.md

@@ -1,9 +1,11 @@
 # Backlog — 0.3.0 and later
 
 Recorded after hands-on testing of 0.2.6.1 in September 2026. **None of
-this is in 0.2.6.2 or 0.2.6.3**: 0.2.6.2 is limited to picture printing,
-the Presentations memory failure and the settings lockdown, and 0.2.6.3
-to the black-and-white preview and Print image. Each item says what was
+this is in 0.2.6.2 to 0.2.6.4**: 0.2.6.2 is limited to picture printing,
+the Presentations memory failure and the settings lockdown, 0.2.6.3 to
+the black-and-white preview and Print image, and 0.2.6.4 to temporary
+workspace restore (the two items that were here about links and sign-in
+retention are answered in wonder-ink.md). Each item says what was
 observed, so whoever picks it up starts from the evidence.
 
 ## Wonder Ink
@@ -34,19 +36,20 @@ observed, so whoever picks it up starts from the evidence.
   once Wonder Ink closes — there is no clipboard manager in the session.
   Measured, and judged smaller than leaving the picture there.
 - **A speaker on the tab that is playing sound** (`QWebEnginePage.recentlyAudible`).
-- **Linked lesson text opens an intermediate popup** instead of following
-  the link, where Chrome follows it directly. Investigate: probably a
-  site script choosing `window.open` for a gesture Wonder Ink reports
-  differently, or `createWindow` being asked for a popup type we treat as
-  a tab.
-- **Session retention.** Today closing Wonder Ink signs the teacher out
-  (session-only cookies). Wanted: recover from an accidental close, but
-  expire after a configurable period of inactivity, including across
-  restarts. Needs a design that never leaves one teacher signed in for
-  the next — and first, a real account to measure where the site keeps
-  its sign-in: 0.2.6.1 found cookies do clear on close, but the profile's
-  Local Storage persists, and whether the site stores its token there has
-  never been tested.
+- **A picture in its own tab, in a room above 100%** (seen testing
+  0.2.6.4). Page zoom is the room's `UI_SCALE`, and the engine's picture
+  viewer takes it too, so at 200% a slide opened from a lesson is shown
+  twice its size with scrollbars rather than fitted to the window, as
+  Chrome shows it. Printing is unaffected.
+- **Staying signed in, if WonderInk ever issues a real session token.**
+  Today its sign-in is the teacher's email and password in a Basic-auth
+  cookie (measured, 0.2.6.4), so keeping it would mean keeping a password;
+  Wonder Ink does not. Worth asking WonderInk for a server-issued token
+  that can be revoked; until then, closing Wonder Ink signs the teacher
+  out, and only the recent tabs come back.
+- **Workspace time as a room setting**, if two hours turns out wrong for
+  some room: `IDLE_LIMIT_SECONDS` in `classroom_wonderink_workspace.py` is
+  the one place, and a device.conf key would be a small change.
 - **The site's sluggishness, where it is ours.** Measured in 0.2.6.1:
   Wonder Ink and Chrome take the same time (about 2.9 s cold) and the
   site is the weight — 119 – 160 requests, 3.2 MB, the Google Maps API