Fix the duplicate charge guard in an SQS consumer

An SQS queue triggers your Lambda, which charges customers for orders. A standard SQS queue delivers at least once: the same message can arrive twice, for example after a timeout or a retry. Finance found duplicate charges. So the consumer now uses the order id as an idempotency key, a key that makes a repeated request do nothing the second time.

An assistant wrote charge_orders_idempotently(delivered_order_ids). It is in the editor. It has a bug. Find it and fix it.

Input and output:

• delivered_order_ids: the order id in each delivery, in delivery order, redeliveries included. Each id is a string. It can have whitespace around it, and it can be empty or all whitespace.
• Return a list of strings, one per delivery, in the same order. Each is "charged", "duplicate_skipped" or "invalid_skipped".

Rules the tests check:

• Trim whitespace (spaces, tabs, newlines) at both ends of each id. The trimmed id is the order's key.
• A delivery whose key is empty gets "invalid_skipped". It does not claim a key.
• A delivery whose key was already charged by an earlier delivery gets "duplicate_skipped".
• Any other delivery gets "charged", and its key counts as charged from then on.
• Keys compare exactly. Case matters: ORD-1 and ord-1 are different orders.
• An empty list returns an empty list.