Export now includes invoice_payments and recurring_invoices tables.
Import restored to use ID-based lookups and all fields for clients,
projects, tasks, and time entries. Added missing import support for
timeline_events, calendar_sources, calendar_events, invoice_payments,
and recurring_invoices. Export uses native save dialog instead of blob
download. Removed sample data seeding (seed.rs, UI, command).
eb0c65c29a