Scroll speeds below 1 dot per second

scroll_speed is now a float (0.05-30 dots per second, e.g. 0.25 = one dot
every 4 s). Page format 5; version 4 pages are converted, version 3 goes
through version 4.

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

src/esp32/web/page_json.cpp

@@ -124,7 +124,7 @@ const char *pageFromJson(JsonVariantConst in, DynamicPage &page)
 		e.decimals = constrain(o["decimals"] | (int)DECIMALS_AS_IS, -100, 100);
 		e.factor = o["factor"] | 1.0f;
 		e.scroll_width = constrain(o["scroll_width"] | 0, 0, 255);
-		e.scroll_speed = constrain(o["scroll_speed"] | 8, 0, 255);
+		e.scroll_speed = o["scroll_speed"] | 8.0f; // checked in validatePage()
 		int show = indexOf(SHOWS, o["show"] | "number"), unit = indexOf(UNITS, o["input_unit"] | "s");
 		if (show < 0 || unit < 0)
 			return "Unknown Home Assistant value setting";