[Bug]: Perps modal incorrectly shown when navigating back from Market Details page instead of on banner tap

### Describe the bug

After onboarding with an existing SRP, when the user clicks a **Perps banner** on the homepage, the Market Details page is displayed as expected. However, when the user clicks the **back arrow** to return to the homepage, the **Perps modal is triggered** — this modal should only appear when the user clicks the banner, not when closing the Market Details page.

### Expected behavior

The Perps modal should be displayed **when the user clicks the Perps banner** on the homepage. Navigating back from the Market Details page should return the user cleanly to the homepage without showing any modal.

### Screenshots/Recordings

https://www.loom.com/share/f67d36a688a64c4ba9d0d45083039059

### Steps to reproduce

1. Onboard using an **existing SRP**
2. On the homepage, click a **Perps banner**
3. The **Market Details page** is displayed
4. Click the **back arrow** to return to the homepage
5. Observe that the **Perps modal appears** unexpectedly

### Error messages or log output

_No error message displayed._

### Where was this bug found?

Internal release testing

### Version

13.36.0

### Build type

_No response_

### Browser

Chrome

### Operating system

MacOS

### Hardware wallet

_No response_

### Additional context

- Onboarding method: existing SRP import
- The Perps modal is triggered on back navigation from Market Details instead of on banner click
- This suggests the modal display logic is tied to the navigation stack dismissal rather than the banner click action
- Team: Social

### Severity

_To be filled by internal support / PM_

Reproduce the flow in Chrome using an existing SRP: tap the Perps banner on the homepage, open Market Details, then use the back arrow. Trace the homepage banner, Market Details navigation, and Perps modal handling; done means the modal appears on banner tap but not when returning from Market Details.

Written by the indexing model from the issue text.