Export to CSV should show persistent in-page success notification at top

[Jahnavidarisetti]

Problem
Clicking “Export to CSV” shows a popup/notification that disappears after a few seconds. The feedback isn’t visible long enough and isn’t placed where users look.

Expected behavior

• After a successful export, show a persistent in-page success notification at the top of the page.
• The notification should be located just above the “Back to Menu” button.
• It should not auto-dismiss after a few seconds.

Acceptance criteria

• Successful export triggers an in-page notification (not a transient popup).
• Notification is displayed at the top of the page above “Back to Menu”.
• Notification remains visible until the user navigates away or explicitly dismisses it.