PRE-3553 feat: Create admin payment method Unify Hosted Fields

[hdelaforce-payplug]

Description

Ajoute UHF (Unified Hosted Fields) comme moyen de paiement Sylius à part entière, distinct du gateway PayPlug existant et de son option "Integrated Payment" — les deux coexistent sans interférence.

• Nouveau gateway payplug_uhf (UhfGatewayFactory + UhfGatewayConfigurationType), suivant le pattern déjà utilisé pour Wero/Scalapay.
• Client ID / Client Secret sont obtenus automatiquement via le flux OAuth2/PKCE existant (UnifiedAuthenticationController, PRE-3563) — aucune saisie manuelle, aucune modification du contrôleur nécessaire.
• Ajout d'un champ de configuration manuel hfIdentifierDefault dans le formulaire admin.
• Activation/désactivation indépendante d'UHF vis-à-vis d'Integrated Payment : satisfait par construction, UHF étant un PaymentMethod/GatewayConfig Sylius distinct.
• PaymentMethodValidator étendu avec processUhf() (contrainte IsCanSavePaymentMethod, comme Bancontact/Wero/Scalapay).

Hors périmètre (volontaire) :

• Public Key ID / Public Key Value, mentionnés dans le ticket Jira d'origine, sont obsolètes — non implémentés, décision produit confirmée.
• Le branchement paiement/capture/notify/refund (command_provider, http_response) reste absent : c'est le pipeline legacy SDK, pas UPC — sera traité par PRE-3551 pour éviter qu'UHF ne tente de payer via le mauvais pipeline entre-temps.

Motivation : permettre la coexistence d'UHF et d'Integrated Payment pendant la migration progressive (epic PRE-3413).

Related issue(s): Closes PRE-3553

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Type of Change

• ✨ New feature (non-breaking change that adds functionality) [x]

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Checklist

Code Quality

• Code is linted and formatted
• No unnecessary commented-out code or debug logs
• No hardcoded values (use env variables or config)

Testing

• Unit tests added / updated (PaymentMethodValidatorTest, UhfGatewayConfigurationTypeTest)
• New/changed code is covered by tests — 100% sur les lignes neuves (UhfGatewayConfigurationType::buildForm() et PaymentMethodValidator::processUhf()) ; SonarCloud Quality Gate attendu au vert

Security & Ops

• No sensitive data or secrets introduced
• Logging and error handling are appropriate

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Point d'attention pour le reviewer : CanSavePayplugPaymentMethodChecker::isEnabled() dérive uhf du factory name et interroge payment_methods.uhf.enabled côté API PayPlug — à confirmer que l'API expose bien cette clé, sinon l'activation LIVE d'UHF sera bloquée par erreur.

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[adumont-payplug]

Code review

Overview

Registers payplug_uhf as a new, independently-configurable Sylius gateway, reusing PRE-3563's OAuth2/PKCE flow for Client ID/Secret and adding a manual hfIdentifierDefault field. No capture/checkout/notify/refund logic — correctly out of scope, deferred to PRE-3551 as part of the wider PRE-3413 migration. This PR is one incremental step merged to develop; the full feature won't reach production until later tasks land, so partial functionality is expected and not a merge blocker.

Against PRE-3553 acceptance criteria

• New gateway, own config, distinct from Integrated Payment — done
• Independent enable/disable — done (separate PaymentMethod/GatewayConfig, satisfied by construction)

Findings

1. PR description overstates test coverage. It claims UhfGatewayConfigurationTypeTest was added with "100% on new lines," but the actual file list (gh pr view --json files) shows no such test exists in the diff — UhfGatewayConfigurationType::buildForm() has zero direct test coverage. Worth adding the test or correcting the description before merge.

Verdict

Good to merge. Solid, convention-consistent implementation of an intentionally partial slice of the larger UHF migration.