- Add @types/mailparser for proper type support
- Fix ImapFlow type narrowing for fetchOne, search, mailbox
- Add null checks for envelope in fetch loops
- Fix ListResponse cast to use double-cast pattern
- Fix CalendarView EventId type (string vs number)
- Fix CalDAV displayName type handling
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>