feat(wallet): Bitcoin Connect NWC "Connect wallet" flow [LOCAL — flag ON, do not push as-is]

Phase 0+1 of docs/bitcoin-connect-plan.md (#61). Adds Alby's Bitcoin Connect as a
one-tap NWC connect front-end that feeds bitvid's EXISTING wallet pipeline; manual
URI entry stays as the backup.

- Vendored: pinned @getalby/[email protected].3 bundled by
  scripts/build-bitcoin-connect.mjs → vendor/bitcoin-connect.bundle.min.js (esbuild,
  browser ESM). crypto-shim aliases the L402-only `import('crypto')` bitvid never
  calls. `npm run build:bitcoin-connect` rebuilds it.
- Flag: FEATURE_BITCOIN_CONNECT wired like FEATURE_AUDIO_INGEST
  (instance-config → config → constants).
- UI: a "Connect wallet" button in the Wallet Connect pane (hidden unless the flag
  is on); the manual URI field stays below as the backup.
- Controller: ProfileWalletController.handleBitcoinConnect() lazy-imports the bundle
  (only on click — the ~700KB never touches the main bundle), inits NWC-only with
  least-privilege requestMethods and persistConnection:false, then on onConnected
  extracts provider.client.nostrWalletConnectUrl → the SAME validate→save path as
  the manual field → disconnect() so bitvid solely holds the spending secret. The
  URI is never logged.

NOTE: config/instance-config.js FEATURE_BITCOIN_CONNECT is TRUE for local testing
only. Reset to false (shipping default) before pushing/deploying. Local commit;
not pushed, not deployed.

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

scripts/build-bitcoin-connect.mjs

@@ -0,0 +1,51 @@
+// Bundles Alby's Bitcoin Connect into a single self-contained ESM file that
+// bitvid lazy-imports behind FEATURE_BITCOIN_CONNECT (docs/bitcoin-connect-plan.md).
+// Mirrors the floating-ui vendor step in build-beacon.mjs. Pinned via the exact
+// devDependency version in package.json.
+import { build } from "esbuild";
+import { mkdir, copyFile } from "node:fs/promises";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..");
+const entryPoint = path.join(repoRoot, "scripts/vendor/bitcoin-connect-entry.mjs");
+const vendorDir = path.join(repoRoot, "vendor");
+const outFile = path.join(vendorDir, "bitcoin-connect.bundle.min.js");
+const licenseSrc = path.join(
+  repoRoot,
+  "node_modules/@getalby/bitcoin-connect/LICENSE",
+);
+const licenseOut = path.join(vendorDir, "bitcoin-connect.LICENSE");
+
+await mkdir(vendorDir, { recursive: true });
+
+await build({
+  bundle: true,
+  entryPoints: [entryPoint],
+  outfile: outFile,
+  format: "esm",
+  splitting: false,
+  platform: "browser",
+  target: ["es2020"],
+  minify: true,
+  sourcemap: false,
+  define: {
+    "process.env.NODE_ENV": '"production"',
+    global: "globalThis",
+  },
+  // @getalby/lightning-tools lazily `import('crypto')` for L402 macaroons — a
+  // path bitvid never calls. Alias it to a browser shim so the bundle resolves.
+  alias: {
+    crypto: path.join(repoRoot, "scripts/vendor/crypto-shim.mjs"),
+    "node:crypto": path.join(repoRoot, "scripts/vendor/crypto-shim.mjs"),
+  },
+  logLevel: "info",
+});
+
+try {
+  await copyFile(licenseSrc, licenseOut);
+} catch (error) {
+  console.warn("[build-bitcoin-connect] could not copy LICENSE:", error.message);
+}
+
+console.log("[build-bitcoin-connect] wrote", path.relative(repoRoot, outFile));

scripts/vendor/bitcoin-connect-entry.mjs

@@ -0,0 +1,17 @@
+// Vendor entry for Alby's Bitcoin Connect (getalby/bitcoin-connect), bundled by
+// scripts/build-bitcoin-connect.mjs into vendor/bitcoin-connect.bundle.min.js so
+// bitvid can lazy-import it behind FEATURE_BITCOIN_CONNECT without a runtime CDN.
+//
+// Importing the package self-registers its web components (bc-modal, etc.), so a
+// single import both loads the API and boots the UI. We re-export only the small
+// surface ProfileWalletController needs. See docs/bitcoin-connect-plan.md.
+export {
+  init,
+  launchModal,
+  closeModal,
+  onConnected,
+  onDisconnected,
+  disconnect,
+  getConnectorConfig,
+  isConnected,
+} from "@getalby/bitcoin-connect";

scripts/vendor/crypto-shim.mjs

@@ -0,0 +1,26 @@
+// Minimal browser shim for node's `crypto`, aliased in when bundling Bitcoin
+// Connect (scripts/build-bitcoin-connect.mjs). The only place its deps reach for
+// `crypto` is @getalby/lightning-tools' L402 macaroon helpers via a lazy
+// `await import('crypto')` — a path bitvid's NWC connect/pay flow never calls.
+// timingSafeEqual is implemented properly; the L402-only createHmac is stubbed so
+// it fails loudly rather than silently misbehaving if ever reached.
+export function timingSafeEqual(a, b) {
+  const ua = a instanceof Uint8Array ? a : new Uint8Array(a);
+  const ub = b instanceof Uint8Array ? b : new Uint8Array(b);
+  if (ua.length !== ub.length) {
+    return false;
+  }
+  let diff = 0;
+  for (let i = 0; i < ua.length; i += 1) {
+    diff |= ua[i] ^ ub[i];
+  }
+  return diff === 0;
+}
+
+export function createHmac() {
+  throw new Error(
+    "createHmac (L402 macaroons) is not available in the bitvid browser bundle",
+  );
+}
+
+export default { timingSafeEqual, createHmac };