Cast default values to int to prevent null‐default TypeError in closure

[ikramagix]

⚠️ Disclaimer: This is NOT A FIX (yet). This is a temporary unblock to let the upgrade or install complete.

This PR provides a workaround for Issue #22, preventing the fatal Argument #3 must be of type int, null given error on Moodle 4.5.1 when upgrading format_cards v1.5.0.

What it does:

• In course/format/cards/lib.php, every default value passed into the createselect closure is explicitly cast to int (i.e. (int) $defaults->…) with FORMAT_CARDS_USEDEFAULT as the fallback.
• No other rendering or course‐format logic is modified.

Why it’s only a workaround:

• It unsticks the upgrade/install by stopping the crash, but subsections will NOT render as cards until a proper upstream fix is applied or you downgrade to a previous plugin version.

• Administrators can now regain access to the UI and uninstall or revert as needed.

How this PR can help you:

1. Replace your lib.php with this patched version.
2. Purge caches (Site Admin → Development → Purge all caches or php admin/cli/purge_caches.php).
3. Proceed with upgrade, uninstall, or downgrade.

Purpose of this PR:
Provide the updated lib.php content as a base for anyone to restore their Moodle platform and as a starting point for fully fixing Issue #22.