style(web_server.py): fix typing errors

src/judas_server/web/web_server.py

@@ -85,7 +85,7 @@ def index() -> flask.Response | str:
 
 
 @app.route("/login", methods=["GET", "POST"])
-def login() -> str:
+def login() -> flask.Response | str:
     """Handles user login via password form."""
     if flask.request.method == "POST":
         password = flask.request.form.get("password", "")