Sending a zap to a creator whose LNURL endpoint is down or doesn't send
CORS headers (e.g. unitypay.cash/.well-known/lnurlp/<name>) made the browser
fetch reject with a raw "Failed to fetch", which bubbled up as the zap's
error toast — the "clunky errors" reported during the zap audit.
fetchPayServiceData now catches the network/CORS rejection and throws a
clear, coded error ("Couldn't reach this recipient's Lightning address. It
may be offline or blocking browser requests."), preserving the original as
`cause`. Non-OK HTTP and valid responses are unchanged.
Part of the zap audit (TODO #3). Also recorded: the video-modal popover
mis-positioning (3a) and that the deeper CORS issue (static client can't
fetch CORS-less LNURL hosts) may need a proxy — tracked separately.
Tests + mutation-verified. 1274 pass (known UploadModal flake).
Co-Authored-By: Claude Opus 4.8 <[email protected]>
