When viewing the Sent or Drafts mailbox, the list items always
displayed the sender (email.from[0]) — which is always the logged-in
user — instead of the recipient. This makes it impossible to
identify messages by who they were sent to.
This change detects the current mailbox role from the store and
swaps the displayed person to email.to[0] when the role is 'sent'
or 'drafts'. For multi-email threads, participant names are
computed from the collected recipients of the thread's emails.
Affected components:
- EmailListItem (flat list, threading disabled)
- SingleEmailItem (single-email thread)
- ThreadListItem (multi-email thread header + avatar)
This matches the behaviour of Gmail, Outlook, Apple Mail, and
every other mainstream mail client.
