Create Feature Tests - Attendance API

Description

Write feature tests for Attendance API endpoints.

Acceptance Criteria

• test_can_get_event_attendance
• test_can_submit_rsvp
• test_can_update_rsvp
• test_unique_constraint_enforced
• All tests passing

Implementation Steps

1. php artisan make:test AttendanceApiTest
2. Write test cases
3. Test updateOrCreate behavior
4. Run tests

Reference

• Roadmap: docs/roadmaps/Implementation_Roadmap_Backend.md Phase 7
• Standards: backend/CLAUDE.md

Related Issues

• Depends on: #9 (closed)