fix(display): schedule windows end at the end time; on-demand ending in off hours blanks at once (#714)

Schedule and dim windows are half-open [start, end): on from the start time, off at exactly the end time, whatever second the check runs. An on-demand session that ends in scheduled-off hours (expiry or stop) clears the once-a-minute schedule gate, so the panel blanks within about a second. Golden: schedule; two test_display_pending_changes.py tests now say end_time 23:00.

Merged with #712 and #713: with all three in, docs/RUN_LOOP_REDESIGN.md's 'may be wrong' list is empty, so that section now records that all six items are fixed and by which PR.

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

CHANGELOG.md

@@ -110,6 +110,17 @@ policies are unchanged.
   screen showed first and the game came after it. Each check also asks each
   plugin `has_live_content()` once, where a plugin registered under several
   modes used to be asked once per mode.
+- The display schedule turns the panel off at exactly the end time. A window
+  now runs from its start time up to, but not including, its end time: with
+  07:00-23:00 the panel is on at 07:00 and off at 23:00. Before, the end
+  minute counted as on, and because the schedule is checked once a minute,
+  the panel went off at 23:00 or at 23:01 depending on when in the minute
+  that check ran. Windows that cross midnight and per-day schedules follow
+  the same rule, and so does the dim schedule.
+- An on-demand session that ends during scheduled-off hours, by expiring or
+  being stopped, blanks the panel within about a second. It used to stay on
+  until the next minute, because the once-a-minute schedule check had
+  already run that minute and the session had overridden its answer.
 
 ## 3.8.0