Phase 8b Task 2. @resvg/resvg-js renders public/icons/source.svg
into the four PNG sizes the manifest + iOS expect: 192, 512,
maskable-512 (Android safe-zone), and apple-touch-icon-180.
Build is one-shot — outputs are committed, runtime doesn't ship
the dep.
Phase 8b Task 1. Rounded-square brand tile with a single white
exclamation mark. Colour matches src/lib/brand-default.ts. Tasks 2
or later rasterise this into the four PNGs the manifest + iOS
expect.
