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>

docs/web-ui.md

@@ -40,7 +40,7 @@ arrow keys. Built-in pages can be copied, not changed. See the [pictures of the
 
 Every element has a position, alignment, font and overlay (on top, box that clears the
 dots behind it, inverted). Entity ids can contain `{plex_user}`, replaced by the Plex user
-of the Home Assistant tab (e.g. `sensor.{plex_user}_state`). Texts can scroll in a window at a chosen speed and can contain
+of the Home Assistant tab (e.g. `sensor.{plex_user}_state`). Texts can scroll in a window at a chosen speed (0.05-30 dots per second, e.g. 0.25 = one dot every 4 s) and can contain
 the degree sign. Fonts: Small (3x5), Normal (5x7), Large (5x7 doubled), Full height (19 dot
 digits), and your own: upload a TTF/OTF, choose the height in dots, the browser converts
 it.