ui: enlarge the header sim/nosim icon to 30px

- the SVG artwork occupies only ~46% x 63% of its 183x183 canvas, so
  the 18px render showed ~8x11px of ink; 30px roughly doubles the
  visible glyph while staying under the 32px h1 line-height, so the
  header row height is unchanged
- guard test asserts the inline size stays within the 24-32px budget;
  SW cache v112 -> v113.

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'otaman-v112';
+const CACHE = 'otaman-v113';
 const URLS = [
   'index.html',
   'help.html',