I've got an orders export (orders.csv) and our customer table (customers.csv) in this folder. Before we load orders into the warehouse each night, I want a data quality check suite. Write it in Python (standard library only, pandas isn't installed; sqlite3 is fine), run it against these files, and give me a short summary of what passed and what failed.

Write the rules from these business definitions, not from what you see in the file.
List every threshold and tolerance you choose, and why, before you use it.
Put them all in one config file that a human signs off.

Business definitions:
- Which order statuses must have a ship date, and which must not.
- Which currencies and countries we sell in today.
- How amounts are calculated and rounded (and whether refunds are negative).
- Anything else that is a rule here, not just a pattern in this file.
