pnpm to npm

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: francisco-videira-nhs

tests/helpers/pnpm-helpers.ts

@@ -75,11 +75,11 @@ export async function runCreateLetter(options: {
       output += text;
       process.stdout.write(text);
     });
-    child.on("close", (code) => {
       if (code !== 0) {
-        reject(new Error(`pnpm exited with ${code}`));
+        reject(new Error(`npm exited with ${code}`));
         return;
       }
+      }
 
       const letterIdsMatch = /LETTER_IDS:(\[[^\n]*\])/.exec(output);
       if (!letterIdsMatch) {