The list endpoints now return a total count alongside the page so the
front-end can show how many pages exist and offer a last-page jump.
Backend: add count(is_new) and count_devices(...) (sharing a WHERE-builder
with list_devices so page and count can't drift), wrap both list responses
in {items, total_count} structs, and register them with utoipa.
Front-end: parse the wrapper shape (dropping the fetch-one-extra trick),
add a Last-page button and a responsive "Page X of Y" / "X / Y" label to
the shared PaginationBar, and track the total in both lists. Notifications
re-sync the count on every fetch and decrement it locally on mark-read/
unread removals so the count stays accurate without a re-fetch.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Break the 372-line frontend API client into focused files under
lib/utils/api/: error mapping (api_error.dart), Dio setup behind a
buildDio factory (dio_config.dart), and device/scanner/notification
endpoints as extensions in part files. Collapse the five near-identical
scanner-status methods via a generic _getModel helper and de-duplicate
the pagination logic via a shared _paginate helper.
The BackendAPI singleton and dioErrorToUserMessage remain importable
from oott_api.dart unchanged, so no call sites are affected.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
