esim: show the profile icon image and its data size

pySim already requests the Icon tag (0x94) together with the other
ProfileInfo tags; the mapping dropped it, so the PWA only had the icon
type.

- esim.profiles(): each profile now carries `icon` (the image bytes as
  hex) and `icon_size` (byte count), null when the card sent no image.
- PWA: esimIconDataUrl() builds a data: URL (png/jpg -> image/png|jpeg)
  and the profile card shows the image unscaled to the left of the
  metadata rows; the Icon row keeps the type and adds the data size
  (e.g. 'png · 1234 B').
- tests: profiles icon/icon_size mapping (+ the absent case) and the
  frontend data URL / row / render checks; docs and sw simple-v231.

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'simple-v230';
+const CACHE = 'simple-v231';
 const URLS = [
   'index.html',
   'help.html',