feat(frontend): bundle the icons so the app works offline

Every <wa-icon> was fetched from ka-f.fontawesome.com at runtime —
confirmed from `performance.getEntriesByType('resource')`, 36 requests
— so offline the app had no icons at all. `setBasePath()` does not
affect the icon resolver; only the component autoloader reads it.
Overriding Web Awesome's `default` icon library fixes all 165 call
sites without changing one of them. Cross-origin requests at startup:
22 -> 0.

Three things about it are load-bearing. The set is Font Awesome Free
(CC BY 4.0, vendored with its licence by `scripts/fetch-icons.mjs`)
because the kit CDN serves Pro, which cannot be redistributed. The
names are a committed list rather than anything derived, because
twenty call sites compute their icon name from state and no static
pass can enumerate them. And a name that is not bundled is reported at
runtime to `window.__yjIconMisses` and drawn as a fallback, since a
missing icon used to be impossible — the CDN having had everything.

frontend/src/assets/icons/fa/solid/box-open.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 640 512"><!--! Font Awesome Free 7.3.1 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2026 Fonticons, Inc. --><path fill="currentColor" d="M560.3 237.2c10.4 11.8 28.3 14.4 41.8 5.5 14.7-9.8 18.7-29.7 8.9-44.4l-48-72c-2.8-4.2-6.6-7.7-11.1-10.2L351.4 4.7c-19.3-10.7-42.8-10.7-62.2 0L88.8 116c-5.4 3-9.7 7.4-12.6 12.8L27.7 218.7c-12.6 23.4-3.8 52.5 19.6 65.1l33 17.7 0 53.3c0 23 12.4 44.3 32.4 55.7l176 99.7c19.6 11.1 43.5 11.1 63.1 0l176-99.7c20.1-11.4 32.4-32.6 32.4-55.7l0-117.5zm-240-9.8L170.2 144 320.3 60.6 470.4 144 320.3 227.4zm-41.5 50.2l-21.3 46.2-165.8-88.8 25.4-47.2 161.7 89.8z"/></svg>