Refactor login_required and add auth blueprint

Moved the login_required logic to a new utils.py for reuse. Added a new auth blueprint and registered it in app.py. Updated user blueprint to use the shared login_required function.

application/user/routes.py

@@ -12,6 +12,7 @@ from application import db
 from forms import FoodItemForm
 from models import FoodItem, FoodLog
 from datetime import datetime, timezone, timedelta
+from application.utils import login_required
 
 user_bp = Blueprint(
     "user",
@@ -20,10 +21,7 @@ user_bp = Blueprint(
 )
 
 
-@user_bp.before_request
-def login_required():
-    if not current_user.is_authenticated:
-        return redirect(url_for("login"))
+user_bp.before_request(login_required)
 
 
 @user_bp.route("/dashboard", methods=["GET"])