A static client can't fetch LNURL hosts that omit CORS headers, so zaps to
those creators fail. Add a browser-side reachability probe
(checkLightningAddressZappable) and surface it on both sides: the creator
is warned at wallet-connect time if their own address isn't browser-
zappable, and the zapper sees a heads-up when opening a non-reachable
creator's zap dialog.
Also fix encrypted settings restore: the "already offered" flag was
per-pubkey, so once storage was offered the wallet note was never offered
later. Track it per-item so the wallet is offered independently.
Zappability check extracted to walletZappabilityCheck.js for the size cap.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
