Cherry-pick changes from PR #7654: Fix React Native navigation crash

This PR addresses a crash that occurs in React Native when signing in with a password on a new/unrecognized device.

Issue

• In React Native, window exists but window.location is undefined
• When Clerk tries to navigate using new URL(to, window.location.href), it crashes with "Cannot read property 'href' of undefined"

Solution

• Add a check before accessing window.location.href
• If window.location is undefined, use the custom router (routerPush/routerReplace) if provided
• If no custom router is provided, log a warning and return gracefully instead of crashing

Checklist

• Understand the issue from PR fix(clerk-js): Handle missing window.location in React Native navigation #7654
• Explore the repository structure
• Locate the navigate() function in packages/clerk-js/src/core/clerk.ts
• Review existing tests
• Create a changeset file
• Apply the fix to the navigate() function
• Add tests for the React Native scenario
• Run tests to verify the fix
• Run code review
• Run security scan with CodeQL

Cherry-pick the changes from PR #7654 which addresses the following issue:

When signing in with a password on a new/unrecognized device, Clerk's Client Trust feature returns needs_second_factor status. Clerk then tries to navigate to the second-factor UI by calling its internal navigate() function.

The problem: navigate() in packages/clerk-js/src/core/clerk.ts does this:

let toURL = new URL(to, window.location.href);

In React Native:

• window exists (so inBrowser() returns true)
• window.location is undefined
  Result: Crash with "Cannot read property 'href' of undefined"

The fix checks: if window.location is undefined, the navigation will use the custom router provided. If no custom router is provided either, it will log a warning and handle gracefully instead of crashing.

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