implement find by email in json user repo

app/User/JsonUserRepository.php

@@ -50,6 +50,23 @@ class JsonUserRepository implements UserRepository
         return null;
     }
 
+    public function findByEmail(EmailAddress $email): ?User
+    {
+        $users = $this->readUsers();
+
+        foreach ($users as $data) {
+            if ($data['email'] === (string) $email) {
+                return new User(
+                    id: $data['id'],
+                    email: new EmailAddress($data['email']),
+                    isAdmin: $data['isAdmin'] ?? false,
+                );
+            }
+        }
+
+        return null;
+    }
+
     private function readUsers(): array
     {
         if (!file_exists($this->filePath)) {