[mpge]

TL;DR: Adds an optional date cutoff for importing older Shopify orders as history, so backfills preserve current stock instead of treating past sales as new warehouse work.

Orders before the cutoff use core's historical creation path: no stock/bin/serial allocation, reservations, approvals or new-order announcements. Fulfilled history is recorded as shipped and cancelled history as cancelled; later updates remain historical and never restock it. Orders on/after the cutoff retain normal behavior. Mappings and external references keep imports idempotent. Date-filtered records skipped by this version can be revisited as history; manually ignored records remain ignored. Older start dates trigger a clear read_all_orders scope check.

Set the import start date, choose the history cutoff, test the connection and run a full sync. Dates use UTC; variant mappings are required. No shipment is created for a historical order.

Stacked on #4; merge #3 and #4 first. Validation: all 138 plugin tests pass (801 assertions); UI bundle builds. Tests cover zero current stock, repeat deliveries, cancellations, changed cutoffs, ignored records and older-order scopes. No live store was changed.

GitHub-hosted CI currently cannot start: GitHub reports failed account payments or a spending-limit restriction. This is a runner-start restriction, not a build/test failure; the local results above are available for review.