fix(pwa): regenerate app icons from branded favicon (#32)

The PWA icons in public/icons were exported without the Mockingjay
mark, so launchers/home screens showed only the ember-glow background
(a featureless orange blob). Re-render all three sizes from
favicon.svg so the logo appears, and give the maskable variant a
full-bleed background with the mark inside the safe zone.

Co-authored-by: Claude <noreply@anthropic.com>

Author: punyamsingh