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

test/test.pty.ts

@@ -4,6 +4,7 @@ import * as smartshell from '../ts/index.js';
 // Helper to check if node-pty is available
 const isPtyAvailable = async (): Promise<boolean> => {
   try {
+    // @ts-ignore - node-pty is an optional runtime dependency.
     await import('node-pty');
     return true;
   } catch {
@@ -143,4 +144,4 @@ tap.test('Regular pipe mode should still work alongside PTY', async () => {
   expect(result.stdout).toContain('Pipe mode works');
 });
 
-export default tap.start();
+export default tap.start();