fix(unlock-app): Fix flickering in checkout stepper

[0xTxbi]

Description

This PR introduces a fix for a bug causing checkout stepper items to briefly flicker to the minting step after signing in. The update ensures smoother step transitions.

Issues

Fixes #
Refs #

Checklist:

• 1 PR, 1 purpose: my Pull Request applies to a single purpose
• I have commented my code, particularly in hard-to-understand areas
• I have updated the docs to reflect my changes if applicable
• I have added tests (and stories for frontend components) that prove my fix is effective or that my feature works
• I have performed a self-review of my own code
• If my code involves visual changes, I am adding applicable screenshots to this thread