feat(opc): Initialize one page checkout feature

[kevin-carangeot]

Questions	Answers
Context	PrestaShop/PrestaShop#40913
Description?	Initialize new form for OPC feature.
Type?	new feature
BC breaks?	no
Deprecations?	no
Related PR?	PrestaShop/PrestaShop#40864
Sponsor company	PrestaShop
How to test?	Activate OPC feature flag, and go to the checkout.

Integrate the One-Page form skeleton with field validation

Context:

OPC mode should allow a Guest visitor to place an order by providing only their email address + newsletter opt-in. Field validation should be done in real time (or on blur) without completely reloading the page.

Objective:

Create the HTML/CSS/JS integration of the complete OPC form with real-time front-end validation for the Guest journey.

Expected result:

OPC form visually integrated according to the mockups

Functional email and newsletter opt-in fields

Real-time validation (on blur or on input) of fields

No complete page reload during data entry

Inline display of validation errors

[ps-jarvis]

Hello @kevin-carangeot!

This is your first pull request on hummingbird repository of the PrestaShop project.

Thank you, and welcome to this Open Source community!

[tblivet]

Hi @kevin-carangeot,
I am running a shop based on core PR PrestaShop/PrestaShop#40864 and using the current Hummingbird PR.
When I activate the OPC feature flag, nothing changes in the front office is their a missing info in the how to test section?