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>

docs/CONFIG_REFERENCE.md

@@ -31,6 +31,13 @@ tooling against it.
 | `start_time` / `end_time` | `"HH:MM"`, `07:00`–`23:00` | Global-mode on/off times |
 | `days.<weekday>.{enabled,start_time,end_time}` | per-day objects | Per-day-mode overrides |
 
+The display is on from `start_time` up to, but not including, `end_time`:
+with `07:00`–`23:00` it turns on at 07:00 and off at 23:00. An end earlier
+than the start crosses midnight (`22:00`–`07:00` is on overnight). In
+per-day mode, the entry for the current day decides. An on-demand session
+keeps the display on during off hours; once it ends or is stopped, the
+display blanks within about a second.
+
 Read by `DisplayController._check_schedule()` (`src/display_controller.py`).
 Managed in the web UI under Schedule.
 
@@ -44,7 +51,9 @@ Same shape as `schedule` (the template sets its `mode` to `"global"`), plus:
 
 Read by `DisplayController._check_dim_schedule()` (`src/display_controller.py`;
 saved via `POST /api/v3/config/dim-schedule`). The display returns to
-`display.hardware.brightness` outside the window.
+`display.hardware.brightness` outside the window. The window has the same
+boundaries as `schedule`: dimmed from `start_time` up to, but not including,
+`end_time`.
 
 ## `display.hardware` — matrix panel hardware