fix(display): end the scroll before the schedule-off blank and WiFi notice (#721)

The schedule-off blank and the WiFi notice are drawn by the display controller, not dispatched to a plugin, so #716's handover never reached them. Drawn while the last scroll's state was still set, the blank went out with the ticker's lagging rows on a scan-compensated panel and stayed up for its 60 s dwell, and the notice's redraws (which #712 now shows over a running scroller or Vegas) were timed as 0.5-1 s freezes and logged as a mid-scroll Render stall. The controller now calls set_scrolling_state(False) before drawing either; a scroller that resumes sets the state again on its next frame.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -147,6 +147,15 @@ policies are unchanged.
 
 ### Fixes
 
+- The schedule-off blank and the WiFi notice no longer start with a
+  scroller's leftovers. Both are drawn by the display controller rather than
+  dispatched to a plugin, so #716's handover never reached them: drawn while
+  the last scroll's state was still set, the blank went out with the
+  ticker's lagging rows on a scan-compensated panel and stayed up for its
+  60 s dwell, and the notice's redraws (which #712 now shows over a running
+  scroller or Vegas) were counted as 0.5-1 s freezes and logged as a
+  `Render stall ... mid-scroll`. The controller now ends the scroll state
+  before drawing either.
 - A plugin whose `display()` raises now opens its circuit breaker. The first
   frame of each screen goes through the plugin executor, which caught the
   exception and returned False. The display read that as "no content" and