fix: validate cart loop shipping simulation / logged

[hellofanny]

What's the purpose of this pull request?

Infinite loop occurred when validating cart when:

• User was logged in (sessionId present)
• postalCode was set (regionalization active)
• Adding items in cart
• cartEtag changing all the time

You can try simulate the problem here

How it works?

• Change getOrderFormEtag to filter only fields that indicate real cart changes.
• ShippingData verification before early return null: Previously, we returned null immediately when changes.length === 0, ignoring potential need to update shippingData, now we ensures shippingData is updated when necessary (If no changes in the items, but shippingData need to be updated, we update only the shippingData, avoiding inconsistent states.

Scenarios that I've tested:

1. The default one (user logged in + postalCode set)
2. Changing postalCode

testing_fix_changin_postalCode.mov

3. Adding a item that is unavailable (more than one)

testing-no-item.mov

Starters Deploy Preview

preview link

1. Simulates login (using lunellifs acc)
2. Adds a postalCode
3. Adds any item to the cart, try to add more than one.
   The items should be updating according in the card.

References

[coderabbitai]

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