Disable legacy HTTP image hooks by default

hook/InstallKey.php

@@ -2,6 +2,13 @@
 namespace sammo\img_service;
 
 header('Content-Type: application/json');
+if (!file_exists(__DIR__.'/legacy-enabled')) {
+    http_response_code(410);
+    die(json_encode([
+        'result'=>false,
+        'reason'=>'legacy key installation disabled',
+    ]));
+}
 
 
 $json_response = [
@@ -33,4 +40,4 @@ file_put_contents(__DIR__.'/HashKey.php', $keyFile);
 
 $json_response['result'] = true;
 $json_response['reason'] = 'success';
-die(json_encode($json_response));
+die(json_encode($json_response));