Dynamics 365 Business Central: Development - Evolve AL interfaces with default implementations

"Add default method bodies to AL interfaces so existing implementors continue working, then use RequiredPending and analyzer rules to introduce required methods safely.

Business value: Extension publishers can add behavior to an interface without immediately requiring every implementing extension to change. Default methods provide a compatible implementation, while the new transition attribute and AppSourceCop rules support a managed path toward making a method mandatory in a future version. This reduces disruptive interface upgrades and gives dependent developers time to adopt new contracts."