- Extract resolveMailboxByRole() helper shared by both screens so archive
and mark-as-spam use identical dialog-based flows on single and batch actions
- Add Archive button to EmailDetailScreen app bar (was missing)
- Reorder single-mail actions to match batch toolbar: Reply, Forward,
Archive, Delete, Spam, Move, Snooze, Flag
- Move "Mark as unread" from standalone icon button to the popup submenu
- Update _markAsSpam in detail screen to use shared helper (shows
choose/create dialog instead of a bare snackbar when no junk folder)
- Update tests: fix broken snackbar assertion, add tests for Archive
button presence, archive dialog, and mark-as-unread in submenu
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>