Complete SExI SQL take-home solution

[KacperStanczyk]

Summary

• rebuild the employee, expense, supplier, and invoice tables from the supplied source files;
• add reports for manager cycles, expense offenders, and supplier payment plans;
• add focused pytest coverage for the required expense report and document the assumptions and run commands.

Design decisions

• exployee_id is treated as a typo because the CSV and downstream tasks use employee_id;
• the requested invoice_ammount column spelling is preserved;
• cycle output contains actual loop members and excludes employees whose path only enters a loop;
• invoice payments start at the current month end, finish before the due month, and put any cent-level rounding difference in the final payment.

Checks

• Trino 483: all six SQL files executed successfully;
• each loader executed twice after a clean container restart;
• pytest 9.1.1 with trino 0.338.0: 2 passed;
• manual validation: 9 employees, exact expense totals, 3 cycle rows, and 16 payment rows with zero final balance for every supplier;
• Python compilation, dependency versions, git diff --check, and secret scan passed.