Verification URL validity and get-status documentation

We've updated the age verification docs to cover URL validity, expired URLs, and status checks.

What's New

• URL validity: The verification URL is valid for 2 weeks. The expiry is in the JWT token query parameter—use the standard exp claim to check if a URL is still valid.
• Expired URLs: Call /age-verification/get-status with the saved verification ID. If not found, create a new verification.
• Status without the URL: Use get-status with the verification ID to check status anytime (e.g. after URL expiry or if the webhook was missed).
• Retention: Verifications that stay PENDING for over 2 weeks are deleted and no longer returned by get-status.

Updated documentation

• Age verification quick start
• Waterfall flow