Batch actions (delete, move, archive, mark-as-read) performed while
viewing a shared/group mailbox directly from the "Shared" sidebar section
were dispatched to the user's OWN account instead of the shared owner
account. Emails in that view are undecorated (no sourceAccountId, that is
only set in unified/cross-account views) and are reached through the
active client, so they fell into the '__default__' bucket / non-unified
else-branch, which defaults the JMAP accountId to the active account.
batchArchive independently picked the archive folder from the merged
mailbox list, where the user's own archive is listed first.
Stalwart then applies Email/set to the wrong account: because the ids
belong to the shared account it returns them as `updated: null` with an
unchanged state (a silent no-op, not `notUpdated`), so the UI drops the
rows optimistically and they reappear on the next reload. It only appears
to work when the own and shared folder ids happen to collide.
Add resolveViewAccountId() — the owner accountId of the directly-viewed
shared folder (from the selected namespaced mailbox), undefined for a
normal own-account view, mirroring fetchEmails and the single-email path.
Route the four batch actions to that owner account (via the active
client); batchMoveToMailbox also resolves the destination to its bare
originalId, and batchArchive scopes the archive folder to that account.
Own-account and unified/cross-account views are unchanged.
Adds email-store-shared-folder-actions.test.ts covering all four batch
actions in the non-unified shared view plus an own-account regression.
