Summary

• Adds ability to type email addresses in the team event-type assignment dropdown
• Supports comma-separated emails for bulk invites
• Email invites are visually distinguished with “(invite)” label and italic styling

Changes

• Updated CheckedTeamSelect to use CreatableSelect for email input
• Added email validation and comma-separated email parsing utilities
• Added isEmailInvite and email fields to Host and CheckedSelectOption types
• Passed allowEmailInvites prop through AddMembersWithSwitch component chain
• Enabled email invites in EventTeamAssignmentTab for both fixed and round-robin hosts

Test plan

• Go to team event type settings → Assignment tab
• Type an email address in the host selection dropdown
• Verify the email is validated and shown with “(invite)” label
• Test comma-separated emails (e.g., “user1@test.com, user2@test.com”)
• Verify duplicate emails are not added
• Verify existing team member emails are detected

Closes #13532

/claim #13532