fix: fixes token navigation button on the unavailable modal (#26720)

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## **Description**

Problem: The "Change token" button in TokenNotAvailableModal called
navigation.navigate(Routes.RAMP.TOKEN_SELECTION), but the route name
Routes.RAMP.TOKEN_SELECTION exists in both the RootStack (mapped to
MainRoutes, the nested navigator) and the inner Stack (mapped to the
actual TokenSelection screen). After the modal closed via goBack(),
navigate("RampTokenSelection") matched the RootStack's screen, which was
already focused, so React Navigation treated it as a no-op.


Fix: Pass { screen: Routes.RAMP.TOKEN_SELECTION } as the second argument
to navigate, which tells React Navigation to drill into the nested
MainRoutes navigator and navigate to the TokenSelection screen within
it.


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## **Related issues**

Fixes:

## **Manual testing steps**

```gherkin
Feature: my feature name

  Scenario: user [verb for user action]
    Given [describe expected initial app state]

    When user [verb for user action]
    Then [describe expected outcome]
```

## **Screenshots/Recordings**

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### **Before**

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### **After**

![token-button-fix](https://github.com/user-attachments/assets/a602de7f-8809-4067-b928-d3fb431a38ee)

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## **Pre-merge author checklist**

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<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Low risk: small React Navigation parameter change limited to the Ramp
token-unavailable modal, with an updated unit test to lock the behavior.
> 
> **Overview**
> Fixes the `TokenNotAvailableModal` **Change token** button to navigate
into the nested `Routes.RAMP.TOKEN_SELECTION` screen by passing `{
screen: Routes.RAMP.TOKEN_SELECTION }`, avoiding a no-op when the parent
route is already focused.
> 
> Updates the modal’s unit test to assert the new `navigate` call
signature.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
2539270. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: georgeweiler

app/components/UI/Ramp/Views/Modals/TokenNotAvailableModal/TokenNotAvailableModal.test.tsx

@@ -118,7 +118,9 @@ describe('TokenNotAvailableModal', () => {
     fireEvent.press(getByText('Change token'));
 
     expect(mockOnCloseBottomSheet).toHaveBeenCalledWith(expect.any(Function));
-    expect(mockNavigate).toHaveBeenCalledWith(Routes.RAMP.TOKEN_SELECTION);
+    expect(mockNavigate).toHaveBeenCalledWith(Routes.RAMP.TOKEN_SELECTION, {
+      screen: Routes.RAMP.TOKEN_SELECTION,
+    });
   });
 
   it('navigates to provider picker when Change provider is pressed', () => {

app/components/UI/Ramp/Views/Modals/TokenNotAvailableModal/TokenNotAvailableModal.tsx

@@ -51,7 +51,9 @@ function TokenNotAvailableModal() {
 
   const handleChangeToken = useCallback(() => {
     sheetRef.current?.onCloseBottomSheet(() => {
-      navigation.navigate(Routes.RAMP.TOKEN_SELECTION);
+      navigation.navigate(Routes.RAMP.TOKEN_SELECTION, {
+        screen: Routes.RAMP.TOKEN_SELECTION,
+      });
     });
   }, [navigation]);