Add NIP-57 Lightning zaps (npub / lightning address / lnurl)

Send a Lightning zap to a nostr npub, a lightning address (name@domain),
or an lnurl. New src/lnurl.js does the resolution half — target → LNURL-pay
params → signed kind-9734 zap request → callback → bolt11 — and the new
zaps feature (src/features/zaps.js) drives the amount/comment UI, then hands
the invoice to the existing Boltz submarine-swap flow via a new
swaps.startLnPay hook, so there's one tested pay/review/confirm/success path.

Routing: a bolt11 is still caught by swaps; an npub still prefers an instant
free Ark zap when Ark can serve it, and only falls through to a Lightning
zap otherwise — ark's "no Ark address" screen also offers an explicit
"Zap over Lightning" fallback (gated on the zaps feature's canLnZap). A real
zap receipt is attributed only when the server advertises allowsNostr and we
know the recipient's pubkey; otherwise it degrades to a plain LNURL-pay.

Nostr seam gains nostrSign (finalize without publishing), nostrProfile
(kind-0 with lud16/lud06), and nostrRelays. Lightning addresses are
debounced in matchSendText since their regex matches mid-typing.

Verified: unit tests for parse/encode/zap-request; a live resolve→signed
9734→payable mainnet bolt11 against coinos; and an in-browser DOM smoke
(zap form + LNURL params over CORS + allowsNostr hint + handoff).

Co-Authored-By: Claude Opus 4.8 <[email protected]>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/i18n.js b/src/i18n.js
index e439936..04e7e06 100644
--- a/src/i18n.js
+++ b/src/i18n.js
@@ -457,6 +457,17 @@ const STR = {
     lnPayConfirm: 'Pay',
     lnPaySentTitle: 'Lightning payment sent',
     lnPaySentBody: 'The swap provider pays the invoice once the on-chain lockup confirms.',
+    lnZapTitle: 'Zap over Lightning',
+    lnZapReviewTitle: 'Zap over Lightning',
+    lnZapFallback: 'Zap over Lightning instead',
+    lnZapResolving: 'Finding their Lightning address…',
+    lnZapRequesting: 'Requesting a Lightning invoice…',
+    lnZapNoAddress: 'This nostr user hasn’t published a Lightning address.',
+    lnZapRange: 'Enter {min}–{max} sats',
+    lnZapHintNostr: 'Sent over Lightning, with a public zap receipt on nostr.',
+    lnZapHintPlain: 'Sent over Lightning (this address doesn’t support zap receipts).',
+    lnZapSentBody: 'Your zap is on its way — the swap provider pays it once the on-chain lockup confirms.',
+    lnZapFailed: 'Couldn’t complete the zap.',
     spScan: 'Scan for silent payments',
     spScanning: 'Scanning…',
     spWatching: 'Watching for payments',