Add a page schedule with rotation, Home Assistant trigger rules and a Stopwatch tab

- Schedule: daily blocks from a start time, each with up to 6 rotating pages
  or bitmaps (own duration), switching with the effect or instantly. A manual
  pick (Show tab, HA Mode) lasts until the next block; Back to schedule ends it.
- Rules: an HA state (=, is not, above, below) shows a page while true, adds it
  to the rotation while true, or shows it for N seconds when it becomes true.
  Each rule is polled at its own interval, with a 60 s back-off on errors.
- PageSelector (pure logic, tested) decides the shown page; schedule stored in
  NVS; HA sensor Shown page and button Back to schedule.
- Web UI: Schedule and Stopwatch tabs, bitmaps used by pages or rules in their
  own subsection, schedule in export/import. Version 2.6.0.

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

src/esp32/display/frames.cpp

@@ -18,7 +18,8 @@ uint32_t FlipdotFrames::dynamicPage(const LocalTime &time, uint32_t now, bool re
 	bool moving = wait != 0;
 	// The Nano has no acknowledgement: the next frame waits until it has received this one
 	// and flipped its dots, or the next frame overflows its serial buffer
-	uint32_t busy = _show(bitmap, !redraw, moving);
+	uint32_t busy = _show(bitmap, !redraw, moving || _instant_next);
+	_instant_next = false;
 	return moving && wait < busy ? busy : wait;
 }
 
@@ -50,7 +51,8 @@ void FlipdotFrames::noWifi(int hour, int minute)
 
 void FlipdotFrames::page()
 {
-	_drawFullScreen(_page);
+	_show(_page, false, _instant_next);
+	_instant_next = false;
 }
 
 void FlipdotFrames::live()