Add subuser permission evaluation system and extend subuser-related route handling

- Introduce `hasPermission` method in `subusers_o` for permission checks tied to customer context.
- Update `/subusers/me` route to return subuser grants with normalized permissions and metadata.
- Add `get_subuser_customer_number_target` in `authentication` to resolve customer context from request headers.
- Refactor route-level permission checks to handle subuser grants dynamically.
- Introduce CLI test scripts for subuser grants and permission node mappings.
- Add test coverage for subuser grants and permission nodes in new test classes.

services/nginx/app/classes/authentication.php

@@ -181,4 +181,16 @@ class authentication implements authentication_i
         }
         return true;
     }
+
+    public function get_subuser_customer_number_target(): int|false
+    {
+        /**
+         * Decode the headers
+         */
+        $headers = getallheaders();
+        if (!isset($headers['X-Customer-Number'])) {
+            return false;
+        }
+        return (int)$headers['X-Customer-Number'];
+    }
 }