[nobrega8]

Fixes from a 20-point UI checklist audit.

• Radii (14): 17 ad-hoc values collapse to `--r-xs/sm/md/lg/xl` (4/6/8/10/14) so nested corners follow inner = outer − padding.
• Tabular numbers (18): `font-variant-numeric: tabular-nums` on the root, so every column, counter and label lines up.
• Icons (12): the 6 inline SVGs with different viewBox/stroke (play, stop, reset, refresh, external link, heart) now use `Icon.svelte`. Select chevron/check and the library chevrons are left as they are.
• Headings (16): `text-wrap: balance` on h1–h4, `pretty` on paragraphs.
• Layout animation: the scan progress bar scales with `transform` instead of animating `width`. Toaster and `smooth-height` still animate height on purpose.
• Loading (19): buttons with `aria-busy` show a small ring (Import, Install and restart).
• Italics (3): removed from the log note rows and the custom-register group label.

Not changed: badges, text contrast on low-opacity text and the accent colour are design calls, and several checklist points need the app running to judge.

`npm run check` and `npm test` pass (247 tests). I did not run the app, so the visual changes are unchecked on screen.