Mileage
Trip log with IRS rate (edit in Settings). Billable trips can post to an order as a fee line.
Scaffolded, awaiting UI.
Data table mileage_entries exists in both D1 and IndexedDB and syncs
through /api/sync. To flesh out this screen, mirror the pattern
in src/routes/customers/: list page + [id]/ editor
using upsert() from $lib/db/mutations.