Reimburse a month of business mileage with a yearly rate threshold, home-start commute deductions and passengers

# Pay October's mileage claims Inputs: `employees.csv` (normal one-way commute in miles and business miles already claimed this tax year before October), `trips.csv` (October trip log) and `mileage-policy.json`. Work out each employee's mileage payment for October 2026. - Trips with purpose `commute` are not paid and don't count toward any total. - A business trip whose `start` is `home` has the employee's `commute_miles` deducted from its miles (never below 0). That deduction is not business mileage. - Business miles are paid at `rate_high` until the employee's tax-year business miles reach `threshold_miles`, then at `rate_low`. Take trips in date order (then trip_id); a trip that crosses the threshold is split at it. - Each passenger adds `passenger_rate` per business mile of that trip. - Work exactly; round only the reported figures, to 2 decimals half-up. Write `out/mileage.json`: `{"payment": {"<employee_id>": <October payment>, ...}, "business_miles": {"<employee_id>": <October business miles after deductions>, ...}, "total_payment": <sum of the rounded payments>}`. List every employee with a paid trip. ## How this run works - Work on your own: nobody will answer questions in this task, and writing to `ask/` counts against the run. - Write only under `out/`. Create `out/` if it is missing. Inputs are synthetic; don't fetch anything from the network. - Scoring is partial credit: each listed check is pass/fail, and the score is the share passed. Numbers are compared to within 0.005 unless the task says otherwise.