feature: add expiration date input field

[saralvasquez]

Summary of changes

• Adds new text view for expiration date
• Adds formatter class for the expiration input
• Adds tests for the new functionality
• Adds the expiration view to the demo app

Screen_recording_20260514_151517.webm

AI Usage

Which AI Agent Was Used?

• Copilot
• Claude
• Other (Type Name Here)

How was AI used?
I experimented with letting Claude write 100% of this code since there was a lot of context from existing classes. I've thoroughly tested and examined the output, but this is just a note to use a close eye when reviewing this. For what it's worth I had to do very little tweaking on what Claude code put together

Estimated AI Code Contribution

• less than 30%
• 30 - 60%
• 60 - 100%

Checklist

• Added a changelog entry
• Tested and confirmed payment flows affected by this change are functioning as expected

Authors

• @saralvasquez