feat(smartshell): add cwd-aware execution options, structured strict-mode errors, and safer process tree termination

test/test.silent.ts

@@ -62,7 +62,7 @@ tap.test('execStreamingSilent should capture streaming output without console di
   const streamingResult = await testSmartshell.execStreamingSilent('echo "Line 1" && sleep 0.1 && echo "Line 2"');
   
   let capturedData = '';
-  streamingResult.childProcess.stdout.on('data', (data) => {
+  streamingResult.childProcess.stdout!.on('data', (data) => {
     capturedData += data.toString();
   });
   
@@ -101,4 +101,4 @@ tap.test('execSilent vs exec output comparison', async () => {
 
 export default tap.start({
   throwOnError: true,
-});
+});