The settle-up form only exposed from/to/amount and silently dated the
payment by created_at, unlike a regular expense which has an editable
date. Add a settled_at column (independent of created_at, same split as
expense_date) through the schema, migration, service, REST and MCP
surfaces, and the desktop + mobile forms; the ledger groups a payment by
settled_at, falling back to created_at for rows recorded before the
column existed.
RemEx
bd46089450