111 fix no scroll while notifications are showing

[wilhelsr]

Purpose

Allow users to scroll and interact with the page while success notifications are visible.

Changes

• Replace the success notification’s modal dialog with a non-modal popover.
• Preserve the notification’s position, close button, optional action, timer, and slide animation.
• Keep confirmation dialogs modal.

Related issues

None.

Verification

• npm test: all 24 tests passed.
• ESLint and Prettier checks passed for SuccessNotification.tsx.
• npm run build: blocked by an existing unused useNavigate import in AddToBuildButton.tsx.
• Manual browser verification remains: add or remove a component, scroll while the notification is visible, and check its close button, action, and automatic dismissal.

Screenshots

Not applicable — the notification’s appearance is unchanged.

Checklist

• I have reviewed my own changes.
• The changes meet the linked issue's acceptance criteria, where applicable.
• I have verified the changes and recorded the results above.
• I have included screenshots for visual changes, or marked them not applicable.

[krgjert]

Great bug fix!