Add Boltz submarine + reverse swaps (Lightning <-> on-chain)

Non-custodial swaps via Boltz, fully client-side: hal holds the swap key +
preimage and claims (reverse) / refunds (submarine) on-chain via the taproot
script path, so Boltz can never strand funds.

- src/swap.js: tapleaf/tree construction (byte-exact vs boltz-core vectors),
  swap P2TR address derivation (MuSig2 internal key + taptweak), script-path
  claim/refund tx builder, bolt11 decode, Boltz api-v2 client, and a polling
  SwapManager (reverse auto-claim; submarine fund + status + refund).
- wallet.js: deterministic swap-key derivation (dedicated chain) + persistence.
- api.js: configurable Boltz REST/WS endpoints.
- app.js: ⚡ Swap tab — Receive over LN (reverse) + Pay an invoice (submarine).
- tools/swap-*.test.js: vectors, live-address, and end-to-end regtest tests.

Verified end-to-end on regtest against a local Boltz wired to coinos's bc +
a dedicated CLN/hold node.

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

1 files changed, 42 insertions, 0 deletions

diff --git a/tools/swap-vectors.test.js b/tools/swap-vectors.test.js
new file mode 100644
index 0000000..147b114
--- /dev/null
+++ b/tools/swap-vectors.test.js
@@ -0,0 +1,42 @@
+// Verify Hal's swap tapscript/tree construction byte-for-byte against
+// boltz-core's published test vectors (boltz-core/src/bitcoin/scripts/*.rs).
+// Run: bun tools/swap-vectors.test.js
+import {
+  submarineClaimLeaf, reverseClaimLeaf, refundLeaf, swapMerkleRoot,
+  hexToBytes, bytesToHex,
+} from '../src/swap.js';
+import { p2tr, taprootListToTree } from '@scure/btc-signer/payment';
+
+let pass = 0, fail = 0;
+const eq = (name, got, want) => {
+  if (got === want) { pass++; console.log(`  ok  ${name}`); }
+  else { fail++; console.log(`FAIL  ${name}\n   got:  ${got}\n   want: ${want}`); }
+};
+
+// --- swap_tree.rs vector ---
+const claimPk = hexToBytes('814fe2b5ce0e3fe5787fade9a4357a743c4ce6de473e5f29daf42112e47db25a');
+const refundPk = hexToBytes('0095b23ac89f523cdbcd791d3325ada7ddb30fd6134bb7fff22ba1e00414cb7d');
+const ph = hexToBytes('34e64e5b1373a872019ee2c7791cf4264d1079de'); // hash160(preimage)
+
+eq('submarine claim leaf',
+  bytesToHex(submarineClaimLeaf(ph, claimPk)),
+  'a91434e64e5b1373a872019ee2c7791cf4264d1079de8820814fe2b5ce0e3fe5787fade9a4357a743c4ce6de473e5f29daf42112e47db25aac');
+
+// Cross-check our two-leaf merkle root against @scure's own taproot tree
+// builder (BIP341) for the same leaves — proves the TapBranch/sort logic.
+const claim = submarineClaimLeaf(ph, claimPk);
+const refund = refundLeaf(refundPk, 123);
+const scureRoot = bytesToHex(
+  p2tr(claimPk, taprootListToTree([{ script: claim }, { script: refund }]), undefined, true).tapMerkleRoot,
+);
+eq('merkle root matches @scure tree builder', bytesToHex(swapMerkleRoot(claim, refund)), scureRoot);
+
+// --- reverse_tree.rs vector ---
+const rClaimPk = hexToBytes('97f2ea5402afd2e90130e84d97e455f67493a956c20faedce32086516ef9f12e');
+const rPh = hexToBytes('761de3d1f1f54cc8b3beec0a1ad03820a2e12b90');
+eq('reverse claim leaf',
+  bytesToHex(reverseClaimLeaf(rPh, rClaimPk)),
+  '82012088a914761de3d1f1f54cc8b3beec0a1ad03820a2e12b90882097f2ea5402afd2e90130e84d97e455f67493a956c20faedce32086516ef9f12eac');
+
+console.log(`\n${pass} passed, ${fail} failed`);
+process.exit(fail ? 1 : 0);