Mockup for backup encryption

[AmaLuci]

Create a mockup for the parent issue: #1019

Description
Backups will be transmitted to the Nethesis Operation Center if they are encrypted with a passphrase.
For new installations, this will not be an issue, as the passphrase will be a mandatory setting. However, for existing firewalls that do not have a passphrase configured, users may be unaware that their backups will no longer be sent to the Nethesis Operation Center. To address this, we need to introduce UI updates that clearly inform users and prompt them to take action.

Proposed Solution
To ensure users of existing firewalls are notified and encouraged to configure a passphrase, we will introduce the following UI changes:

• Dashboard Card Update
  A new card will be added to the dashboard displaying the timestamp of the last backup. The timestamp will reflect the most recent backup as recorded on Nethesis Operation Center.
  If no passphrase is configured, the card will show a warning badge alerting users that their backups will no longer be sent to the Nethesis Operation Center.

• Inline Notification in the Backup Page
  An inline notification will appear on the backup page if the passphrase is missing.
  The message will inform users that their backups will no longer be stored in the Nethesis Operation Center unless they configure a passphrase.
  They will still have the option to download and restore unencrypted backups locally.

• Modal Update for "Run Backup" Action
  The backup modal will be updated to provide two clear options:
  1- Encrypted Backup (Recommended): The backup will be encrypted, stored securely, and transmitted to the Nethesis Operation Center.
  2- Unencrypted Backup: The backup will be created and available for local download, but it will not be uploaded to the Nethesis Operation Center

[AmaLuci]

Mockups in Figma