Error when trying to save without network connection + toast remains

# File upload QA v2

## Description

When going offline in the middle of the submitting action, one gets brought back to the review page with an error message as expected.

However, if trying to save without network connection (while offline), a toast appears, and remains even once connection is restored.

[Private Zenhub Video](https://api.zenhub.com/attachedFiles/eyJfcmFpbHMiOnsibWVzc2FnZSI6IkJBaHBBM1lIQ3c9PSIsImV4cCI6bnVsbCwicHVyIjoiYmxvYl9pZCJ9fQ==--716f3462b88f6e2a88aada824bf3fff12bb66fd0/Screen%20Recording%202025-08-12%20at%202.56.19%E2%80%AFPM.mov)

Related to #5989

Start by reproducing the offline save flow described under “File upload QA v2,” comparing it with the submitting flow that returns to the review page. Trace the toast behavior while offline and after the connection is restored; done means the error is handled without leaving a persistent toast.

Written by the indexing model from the issue text.