fix(doctor): probe simctl via xcrun instead of PATH lookup

cmd/sanderling/doctor.go

@@ -64,7 +64,7 @@ func androidChecks() []doctorCheck {
 func iosChecks() []doctorCheck {
 	return []doctorCheck{
 		{Name: "xcrun on PATH (ios simulator)", Run: checkExecutableOnPath("xcrun")},
-		{Name: "simctl on PATH (ios simulator)", Run: checkExecutableOnPath("simctl")},
+		{Name: "simctl available (ios simulator)", Run: checkSimctl},
 	}
 }
 
@@ -111,6 +111,15 @@ func checkChromiumLaunch(ctx context.Context) error {
 	return nil
 }
 
+// checkSimctl exercises `xcrun simctl help`: simctl is an xcrun subcommand,
+// not a standalone binary, so a PATH lookup can never find it.
+func checkSimctl(ctx context.Context) error {
+	if err := exec.CommandContext(ctx, "xcrun", "simctl", "help").Run(); err != nil {
+		return fmt.Errorf("xcrun simctl help: %w", err)
+	}
+	return nil
+}
+
 func checkSidecarJAR(_ context.Context) error {
 	if sidecarassets.IsPlaceholder() {
 		return fmt.Errorf("placeholder JAR embedded; run `make sidecar && make sanderling` to embed the real fat JAR")