Clear assignee's existing notifications in setup since Notifier now
uses create_or_find_by instead of create, and reload the association
to avoid caching after destroy_all.
Update fixture references after rebase: use `logo_assignment_kevin`
as base notification and `logo_mentioned_david` for mention tests.
Update source to `logo_published` in tests that need generic card events.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- Add comprehensive integration test covering card assignment, comments,
mentions, email bundling, and edge cases (system user, inactive user)
- Inline push notification test helpers into the only test that uses them
- Remove separate PushNotificationTestHelper module
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>