Offer 98 icons in a dialog and style a button icon under Design

The icon set grows from 33 to 98 drawings in seven categories (arrows,
contact, commerce, files and media, people and security, house and trade,
general), including truck, cart, euro, camera, tools and solar. icons.js is
the single source; npm run build:icons writes the Twig drawings and the
validator list, and a test keeps them equal.

Choosing an icon no longer fills the panel with tiles: the panel shows the
current icon with "Change", which opens a modal with category tabs and named
tiles, keyboard navigable, closing with Escape. Button, icon and icon card
share it.

A new style group "Symbol" targets the icon inside a button per device and
on hover: colour, background, size, padding, radius, rotation, plus the gap
to the text. Schema v26 adds hover motion (slide, reveal) and an icon-only
button whose label stays as the accessible name and keeps the line height.
ADR 109.

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

package.json

@@ -6,6 +6,7 @@
     "build:buttons": "node scripts/build-buttons.mjs",
     "test:buttons": "node scripts/button-check.mjs",
     "test:button-icons": "node scripts/button-icon-check.mjs",
+    "build:icons": "node scripts/build-icons.mjs",
     "test:navigation-ux": "node scripts/navigation-ux-check.mjs",
     "test:responsive-navigation": "node scripts/responsive-navigation-check.mjs",
     "build:design": "node scripts/build-design.mjs",