fix(npm): use spawn with signal handling for graceful shutdown

Replace execFileSync with spawn and add proper signal handling for
SIGTERM, SIGINT, and SIGHUP. This ensures the child process is properly
terminated when the wrapper receives a signal and returns correct exit
codes based on the termination signal.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: manusa

npm/podman-mcp-server/bin/index.js

@@ -21,7 +21,27 @@ const resolveBinaryPath = () => {
   }
 };
 
-childProcess.execFileSync(resolveBinaryPath(), process.argv.slice(2), {
+const child = childProcess.spawn(resolveBinaryPath(), process.argv.slice(2), {
   stdio: 'inherit',
 });
 
+const handleSignal = () => (signal) => {
+  console.log(`Received ${signal}, terminating child process...`);
+  if (child && !child.killed) {
+    child.kill(signal);
+  }
+};
+
+['SIGTERM', 'SIGINT', 'SIGHUP'].forEach((signal) => {
+  process.on(signal, handleSignal(signal));
+});
+
+child.on('close', (code, signal) => {
+  if (signal) {
+    console.log(`Child process terminated by signal: ${signal}`);
+    process.exit(128 + (signal === 'SIGTERM' ? 15 : signal === 'SIGINT' ? 2 : 1));
+  } else {
+    process.exit(code || 0);
+  }
+});
+