Add scrolling, countdown, stopwatch, images, seconds, multiplier and degree sign

- Text elements can scroll in a window at a set speed; clock, countdown and
  stopwatch can show seconds. Moving pages are sent as instant frames (new
  Nano command D1) and paced by the estimated flip time.
- Countdown to a date and time (smart, days, days + time, with seconds),
  stopwatch (web UI, HA switch and reset button), image element (fixed or
  by Home Assistant state), multiplier for HA values, degree sign (char 127)
  in all fonts and the font converter.
- Page format version 2; version 1 pages are converted.

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

src/esp32/logic/display_controller.cpp

@@ -119,7 +119,7 @@ void DisplayController::update(uint32_t now, bool time_valid, const LocalTime &t
 		_off_timer.cancel();
 		_ensureOn();
 		if (_page == Page::Dynamic)
-			_showDynamic(time, show_no_wifi);
+			_showDynamic(now, time, show_no_wifi);
 		else
 			_showOnce(Screen::Page);
 		break;
@@ -139,17 +139,26 @@ void DisplayController::_ensureOn()
 	_screen = Screen::Unknown;
 }
 
-// Drawn again each minute (time, date and background can change) and when the content changed
-void DisplayController::_showDynamic(const LocalTime &time, bool no_wifi)
+// Drawn again each minute (time, date and background can change), when the content changed,
+// and as often as a moving page asks for (scrolling, seconds)
+void DisplayController::_showDynamic(uint32_t now, const LocalTime &time, bool no_wifi)
 {
 	Screen screen = no_wifi ? Screen::NoWifi : Screen::Dynamic;
-	if (_screen == screen && _shown_hour == time.hour && _shown_minute == time.minute &&
-		_shown_revision == _content_revision)
+	bool redraw = _screen != screen || _shown_revision != _content_revision;
+	bool due = screen == Screen::Dynamic && _dynamic_moving && (int32_t)(now - _dynamic_due) >= 0;
+	if (!redraw && !due && _shown_hour == time.hour && _shown_minute == time.minute)
 		return;
 	if (no_wifi)
+	{
 		_frames.noWifi(time.hour, time.minute);
+		_dynamic_moving = false;
+	}
 	else
-		_frames.dynamicPage(time);
+	{
+		uint32_t wait = _frames.dynamicPage(time, now, redraw);
+		_dynamic_moving = wait != 0;
+		_dynamic_due = now + wait;
+	}
 	_screen = screen;
 	_shown_hour = time.hour;
 	_shown_minute = time.minute;