Session-level waiting lists (not block-level)

Summary: Allow waiting lists to operate at an individual session level, rather than only activating when all sessions in a block are full.

Current behaviour
At present, the waiting list only becomes available once all sessions within a block are fully booked. This works well for block or term-based classes, but not for PAYG providers.

Problem
For PAYG providers who only allow customers to book one session at a time, this setup is limiting. If a single session within a block is full, customers cannot join a waiting list for that specific date unless every session in the block is full.

This means:

• Customers cannot express interest in a specific date they want to attend

• Providers miss the chance to capture and understand demand for popular individual sessions

Requested behaviour
Enable waiting lists to be configured per individual session, so that:

• If a specific session is full, a waiting list appears for that session only

• Customers can clearly join a waiting list for a particular date and time

• Providers can notify customers about a particular date in a block, if a space comes available