style(hooks): format signalCode stringification

oxfmt --check rejected the wrapped signal field in runLifecycleHook.

Author: TheGreatAxios

src/session/hooks.ts

@@ -412,8 +412,7 @@ async function runLifecycleHook(
   ]);
   return {
     code: exitCode,
-    signal:
-      proc.signalCode === null ? null : String(proc.signalCode),
+    signal: proc.signalCode === null ? null : String(proc.signalCode),
     stderr: delivered
       ? stderr
       : `${stderr}${stderr.length > 0 && !stderr.endsWith("\n") ? "\n" : ""}hook exited without reading its payload\n`,