[API] Expose collection scheduling metadata needed to interpret card due dates

# Problem

The cards API exposes `RAW_DUE`. For review cards, this is a collection scheduler day number, not a calendar date or Unix timestamp.

External API consumers cannot reliably convert review-card `RAW_DUE` into a concrete calendar date without collection scheduling metadata, such as the collection creation time and day cutoff.

## Proposed follow-up

Expose the collection scheduling metadata needed to interpret review-card due values through the API/content provider

Related comment - https://github.com/ankidroid/Anki-Android/pull/20675#discussion_r3105017577