Open Older

The customer's time before the move to the new site, read live from the old system through Pigeonly and never stored: their older orders (newest first, each with its lines and what was paid) and the notes customer service left then. Each is its own section; the old system being unreachable is legacy_unavailable on that section, never an empty list.

ISS-1996: every Customer Dashboard open asks this, and it reads up to OLDER_MAX_PAGES pages at up to 20 seconds each, so it takes the brief adapter: on _api it held a pool slot for the whole read.