Eviction now goes by the base's signal: `storeLost` and the `store-reset`
notice, with `bulwark-store-opened` as the marker and `prune-files` for files
with no key. The storage page and the lost count hang off that. What a user
picks is stored under `bulwark-offline-scope`, the key `offlineScopeFor`
reads, and `email-snapshot` follows the base's rule. `OfflineEnabled` is read
from the desktop bridge when it's there.
The offline section of Settings > Backup & reset now shows, per account, the
space each part takes, the last sync, a first sync's progress with the time
left, the window and attachment choices, and clearing the account. All
conflicts, calendar and contacts too, are listed there and counted in the
banner.
- the organisation's caps beat the user's choice and the desktop default, and
every path that takes a scope goes through `effectiveScope`
- the desktop app keeps mail without asking, says so once, and stays off for
an account where the user turned it off
- `navigator.storage.persist()` is asked on turning it on, and a refusal
warns with a way to ask again; Safari gets the 7-day hint when not installed
- a store the browser deleted is noticed, says what was lost and syncs again
- a full disk says so, with what to do
- those who had offline mode keep it, with the 30 days they had
- Keep offline in the Files app's menu