Extract uploadAsset/listAssets into utils/assets.ts, lifting the exact
uploadToWhp body and list_assets fetch pattern already duplicated across
shared.tsx/ImageBlock/Logo/Navbar/etc. shared.tsx's uploadToWhp is now a
thin re-export (`export const uploadToWhp = uploadAsset`) so its ~6
existing callers are unaffected.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
