Fix negative volunteer counts caused by observer bug

[edwh]

Summary

• Fixes bug where deleting event invitations incorrectly decremented the volunteer count
• The EventsUsersObserver::deleted() method passed 4 parameters to removed() which only accepts 3, causing the status check to be silently ignored
• Every deleted events_users record was decrementing the count, even for invited (non-confirmed) users who were never counted

Root Cause

Line 89 in EventsUsersObserver.php:

// Bug: 4th parameter is silently ignored
$this->removed($event, $user, true, $eu->status == 1);

// Fix: Pass status check as the $count parameter
$this->removed($event, $user, $eu->status == 1);

Changes

1. One-line fix in EventsUsersObserver.php - correctly pass $eu->status == 1 as the $count parameter
2. Migration to fix all existing events with incorrect volunteer counts
3. Three new tests to prevent regression:
   • testDeletingInvitedVolunteerDoesNotDecrementCount
   • testDeletingConfirmedVolunteerDecrementsCount
   • testMultipleInvitationDeletionsCauseNegativeCount
4. Updated CLAUDE.md with Task/Docker documentation

Test plan

• New unit tests pass locally
• Verify negative counts are fixed after migration runs on staging
• Manual test: invite user to event, delete invitation, verify count stays at 0

[sonarqubecloud]

Quality Gate failed

Failed conditions
25.2% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud