Simulates a complete Interac e-Transfer funding flow.

Using reference: Pass an issueID, t_id, or p_id as the reference field.
The system auto-detects the type. If it resolves to an existing unpaid CAD transaction,
it simulates the Pateno webhook completing it. If it resolves to a p_id, provide amount
to simulate a direct auto-deposit for that user/team.

Using amount only: Creates a new funding transaction for the authenticated user
and processes it immediately.

At least reference or amount must be provided.