[translator] Global cross-collection translation dashboard

## Summary

Translation status is available **per collection** (`get-collection-status`, `useCollectionTranslationStatus`). There is no single view of translation activity across all configured collections. Add a CMS-wide dashboard aggregating queued / in-progress / completed translations.

## Current behavior

- Status endpoints and client hooks are scoped to a single collection.
- The bulk dashboard lives in each collection's list view; there is no global overview.

## Proposed change

- Add an admin view (custom nav item / dashboard) that aggregates translation jobs across **all collections configured in the plugin**: queued / running / completed / failed, with collection + document + target language + timestamp.
- Source the data from the queue and the existing status endpoints across the configured collection set.

## Acceptance criteria

- [ ] A single admin view lists ongoing and recent translations across all configured collections.
- [ ] Each row shows: collection, document, target language, status, timestamp.
- [ ] Reflects live status (running / queued) and recent completions.

## Notes

Listed under the plugin roadmap ("Global translation dashboard"). If lifecycle events are available it can subscribe to those; otherwise it aggregates the per-collection status endpoints.

Start by reading get-collection-status and useCollectionTranslationStatus, then trace how the queue and configured collection set expose translation jobs. Determine the admin view entry point and how live status or lifecycle events are available. Done means one view lists collection, document, target language, status, and timestamp for ongoing and recent translations across all configured collections.

Written by the indexing model from the issue text.