What does this PR do?

Adds an aria-label attribute to the close button in the ProgressToast component to improve accessibility for screen reader users. The button previously had only a visual icon ("x") without a text alternative, making it difficult for assistive technology users to understand its purpose.

• No related GitHub or Linear issue (small accessibility improvement as per CONTRIBUTING.md guidelines)

Visual Demo (For contributors especially)

Code Change:

Before:

<button onClick={() => onClose(toastId)}>
  <Icon name="x" className="h-4 w-4 hover:cursor-pointer" />
</button>

After:

<button onClick={() => onClose(toastId)} aria-label={t("close")}>
  <Icon name="x" className="h-4 w-4 hover:cursor-pointer" />
</button>

The close button now announces "close" to screen readers, making it clear what the button does.

Mandatory Tasks (DO NOT REMOVE)

• I have self-reviewed the code (A decent size PR without self-review might be rejected).
• I have updated the developer docs in /docs if this PR makes changes that would require a documentation change. If N/A, write N/A here and check the checkbox.
• I confirm automated tests are in place that prove my fix is effective or that my feature works.

How should this be tested?

1. Use a screen reader to navigate to the close button
2. Verify it announces "close"
3. Click the button to ensure it works

Environment variables: None

Expected behavior: Close button now accessible to screen readers

Checklist

• I haven't read the contributing guide
• My code doesn't follow the style guidelines of this project
• I haven't checked if my changes generate no new warnings