fix(mongo): confirm before Refresh reloads a dirty document editor

[ZhuchkaTriplesix]

Summary

#782 registers dirty JSON with UnsavedWorkRegistry for Back / Home / Close. Breadcrumb Refresh still bumps refreshToken → MongoDocumentEditor.didUpdateWidget calls _reloadFromServer() with no confirm. Dirty text is replaced from the server (or cleared on error).

Repro

1. Open a document, edit JSON (unsaved).
2. Click Refresh in the explorer breadcrumb.

Expected: discard dialog; Cancel keeps the buffer. Actual: editor reloads; _dirty = false.

Scope

• Confirm via confirmDiscardUnsavedWorkIfNeeded (or editor-local dialog) before _reloadFromServer when _dirty.
• Widget test: dirty editor + refreshToken change does not rewrite text until confirmed.

Out of scope

• Collection-list stale after Save (separate issue).
• Redis string-key Refresh (separate issue).