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>

test/test_display_pending_changes.py

@@ -477,7 +477,7 @@ class TestRunLoopBlanksWhenVegasHandsBack:
         c._cleanup_expired_wifi_status = MagicMock()
         c._refresh_config_cache({
             'display': {'hardware': {'brightness': 90}},
-            'schedule': {'enabled': True, 'start_time': '07:00', 'end_time': '22:59'},
+            'schedule': {'enabled': True, 'start_time': '07:00', 'end_time': '23:00'},
         })
         c.vegas_coordinator = vegas_coordinator(c)
         c.vegas_coordinator._pending_config_update = False
@@ -518,7 +518,7 @@ class TestRunLoopBlanksWhenVegasHandsBack:
         c._refresh_config_cache({
             'display': {'hardware': {'brightness': 90},
                         'display_durations': {'ticker': 120}},
-            'schedule': {'enabled': True, 'start_time': '07:00', 'end_time': '22:59'},
+            'schedule': {'enabled': True, 'start_time': '07:00', 'end_time': '23:00'},
         })
         c.plugin_manager.plugin_executor.execute_display.side_effect = (
             lambda target, plugin_id, force_clear=False, display_mode=None, **kw: