Improve Error Message for Account Deletion with Incorrect Password

### What
When attempting to delete a Simplenote account with an incorrect password, the current error message is: "We could not delete your account. Please try again...".


This message is generic and does not provide any specific guidance to the user.

### Why
Improved messaging will provide users with clearer guidance on how to resolve the issue and successfully delete their accounts.

### How
The error message should be more informative, such as:

- "Incorrect password. Please enter the correct password for your Simplenote account."
- "The password you entered is incorrect. Please double-check and try again."

Start at the account-deletion flow and trace how an incorrect password becomes the current generic error message. Update the displayed message to give clear incorrect-password guidance, then verify the deletion-error state shows the new wording; the issue names no specific files or tests.

Written by the indexing model from the issue text.