fix(node-smol-builder): use socket package bootstrap not local stub

Fix bootstrap path to use packages/socket/dist/bootstrap.js instead of
attempting to create a local stub. The socket package contains the thin
wrapper bootstrap that downloads @socketsecurity/cli on first run.

Architecture:
- packages/socket builds dist/bootstrap.js (thin wrapper)
- node-smol-builder embeds it into Node.js as internal/bootstrap/socketsecurity
- node-sea-builder uses same bootstrap in SEA blob

Previous error:
  Cannot find native builtin: "internal/bootstrap/socketsecurity"
  SIGABRT at startup

Root cause: Bootstrap was not being copied because it was looking in
the wrong location (node-smol-builder/bin/ instead of socket/dist/).

Author: jdalton

packages/node-smol-builder/bin/bootstrap.js

@@ -281,12 +281,14 @@ async function copyBuildAdditions() {
  * (Optional - only runs if bootstrap file exists)
  */
 async function copySocketSecurityBootstrap() {
-  const bootstrapSource = join(ROOT_DIR, 'bin', 'bootstrap.js')
+  // Use bootstrap from socket package (thin wrapper that downloads @socketsecurity/cli).
+  const bootstrapSource = join(ROOT_DIR, '..', 'socket', 'dist', 'bootstrap.js')
 
-  // Skip if bootstrap file doesn't exist yet (future enhancement).
+  // Skip if bootstrap file doesn't exist yet.
   if (!existsSync(bootstrapSource)) {
     logger.log('')
-    logger.log(`${colors.blue('ℹ')} Skipping Socket security bootstrap (bin/bootstrap.js not found)`)
+    logger.log(`${colors.blue('ℹ')} Skipping Socket security bootstrap (packages/socket/dist/bootstrap.js not found)`)
+    logger.log(`${colors.blue('ℹ')} Run 'pnpm --filter socket run build' to create it`)
     logger.log('')
     return
   }