Fix Laravel 5.5 compatibility issues - view helpers, collections, and auth routes

- Replace {{ url() }} with {{ url('/') }} in all blade templates to fix object-to-string conversion errors
- Update TeamStoreModel::selectTeamStoreGroupByCartKey() to use first() instead of get() for Laravel 5.5 Collections
- Fix TeamStoreController to access object properties directly instead of using array syntax [0]
- Update authentication routes to use Laravel 5.5 method names (showLoginForm, login, logout)
- Update login/register links from /auth/login to /login throughout views (navbar, app, auth pages)
- Verify cart, login, and register pages working with HTTP 200 status

test-upgrade.sh

@@ -39,7 +39,7 @@ echo ""
 # Test 3: Database connection
 echo "Test 3: Database Connection"
 echo "----------------------------"
-docker exec $CONTAINER_NAME php artisan tinker --execute="DB::connection()->getPdo(); echo 'DB Connected';" || { echo "❌ Database connection failed"; exit 1; }
+docker exec $CONTAINER_NAME php -r "require 'vendor/autoload.php'; \$app = require_once 'bootstrap/app.php'; \$app->make('Illuminate\Contracts\Console\Kernel')->bootstrap(); try { DB::connection()->getPdo(); echo 'DB Connected\n'; } catch(Exception \$e) { echo 'DB Error: ' . \$e->getMessage() . '\n'; exit(1); }" || { echo "❌ Database connection failed"; exit 1; }
 echo "✓ Database connected"
 echo ""