[FIX] l10n_ar_website_sale_ux: fix AR responsibility field hidden for new customers

[JrAdhoc]

Problem

When a new customer (no ARCA responsibility type set) reached the billing address step in the website checkout, the ARCA Responsibility field was hidden and could not be filled in. Since the field is mandatory for AR companies, the checkout would fail.

Root cause

PR #452 added and responsibility to the outer t-if condition as a workaround for an AttributeError: 'bool' object has no attribute 'name' in a client's database. This condition hides the entire div when the partner has no responsibility set (empty recordset = falsy), creating a catch-22: the field is mandatory, but it's hidden so it can never be filled.

Additionally, the add/separator approach used in #452 kept res_company.country_id.code == 'AR' in the evaluated expression, which is the original variable that may not be available in QWeb context for all users (fixed correctly in #450 by switching to request.env.company).

Fix

Two changes in the same template:

1. Restore the t-if replacement approach (as in [ADD] l10n_ar_website_sale_ux: add portal address templates for company checkout fix #450): set the attribute directly instead of appending, so res_company is no longer evaluated and the div is visible for all billing forms in AR companies regardless of whether responsibility is already set.

2. Guard responsibility.name in the read-only branch: add a safe expression responsibility and responsibility.name or '' on the t-else paragraph to handle cases where responsibility is a bool False instead of a recordset.

Test plan

• New customer with no ARCA responsibility: the responsibility select should be visible at the billing address step and fillable.
• Existing customer with responsibility set: the field displays the current value correctly.
• Existing customer who cannot edit (has issued documents): the read-only paragraph renders without error even if responsibility is unset.

[roboadhoc]

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Updates the AR-specific responsibility section in the portal address form to avoid missing-context errors and to safely render when the partner has no responsibility set.

Changes:

• Replace res_company usage with request.env.company in the AR billing block condition.
• Guard responsibility.name rendering to avoid failures when responsibility is falsy.
• Expand/clarify the intent via an updated XML comment.

[zaoral]

thank you for the PR @JrAdhoc!
@roboadhoc bump r+