Change JumpIn component behavior

The current behavior of the `JumpIn` component in UI2 (`src/components/JumpIn/JumpIn.tsx`) is to display a modal when the launcher is not installed:

```ts
if (!hasLauncher) {
setIsModalOpen(true)
}
```
Problem

Showing the modal in this case is not the expected behavior and results in an inconsistent user experience compared to the landing.

Expected behavior

The component should not open a modal when the launcher is missing.
Instead, it should receive a new property isSignedIn and change its behavior accordingly:

```ts
if (isSignedIn) {
window.open(downloadUrl, '_self')
} else {
window.open(onboardingUrl, '_self')
}
```

Proposed changes
- Add a new prop to JumpIn called isSignedIn.
- Remove the modal logic tied to !hasLauncher.
- Implement the conditional flow based on isSignedIn:
- If true, redirect to downloadUrl.
- If false, redirect to onboardingUrl.

Expected outcome

The JumpIn component will no longer show a modal when the launcher is not present.
Instead, it will handle the user flow directly based on the isSignedIn property, ensuring consistency across dapps.