Steps to reproduce:
- Create a gift card program and a gift card with some balance
- Open a PoS session, add a product to a new order and enter the gift card code: a reward line is added and the total decreases
- Refresh the page, or leave the order and take it back from the Orders screen

Issue:
The reward line disappears and the total goes back to the full price, while the server still holds the pos.order.line with `is_reward_line`, `coupon_id` and `points_cost`. Nothing warns the cashier, so the customer can be charged for a service already paid with the card.

Cause:
`_code_activated_coupon_ids` is a local field of pos.order: it is neither stored in IndexedDB nor sent to the server, so it is empty once the order is rebuilt on the client. `_updateRewardLines` deletes every reward line and only re-applies the ones whose coupon is found in `_code_activated_coupon_ids` or in `uiState.couponPointChanges`. `updatePrograms` only rebuilds the latter for programs detectable from the order content, so a gift card, eWallet or coupon card activated by code is never recognised again and its reward is dropped by the next `updateRewards` call (TicketScreen.setOrder, barcode scan, partner change, line added...).

In 17.0 `codeActivatedCoupons` was exported and restored with the order; the field became local with the 18.0 models rewrite.

Fix:
Add `_restoreCodeActivatedCoupons` on pos.order and call it from `checkMissingCoupons`, which runs once per rebuilt order (`setup` flags it with `invalidCoupons`) before the programs and the reward lines are refreshed. It re-links every persisted coupon referenced by a reward line that is in neither structure. Nominative cards are excluded so that removing the partner still drops their reward.

opw-6568849

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Forward-Port-Of: odoo/odoo#290257
Forward-Port-Of: odoo/odoo#288102