Retrieves complete details of a specific accounting transaction.

The response includes:

• Core transaction attributes (effective_date, description, nature, uuid, journal)
• Associated business object references (bank_transaction_id, billing_line_id, billing_rate_id, upload_id)
• Billing metadata when applicable
• The list of related accounting entries, each including:
  • debit_in_cents / credit_in_cents amounts
  • accounting_account_id
  • Denormalized parent transaction fields: accounting_transaction_nature, accounting_transaction_description, accounting_transaction_effective_date
• The list of related accounting event public IDs