IBX-12652: Added the headless.documentation_url setting

[GrabowskiM]

🎫 Issue	IBX-12652

Related PRs:

• https://github.com/ibexa/page-builder/pull/629
• https://github.com/ibexa/site-context/pull/210

Description:

Adds a headless.documentation_url siteaccess setting next to headless.configuration_url, exposed as HeadlessConfigurationInterface::getDocumentationUrl().

The "headless mode not configured" screens in Page Builder and Site Context link to the documentation on connecting a front-end application. Both had their own hardcoded URL; they now read it from this setting, so there is a single default and installations (e.g. SaaS) can point it to their own guide.

• The default is https://doc.ibexa.co/, marked @todo until the headless documentation page is published.
• Like the other URL getters, an empty value resolves to null; the consuming screens then hide their documentation links.

ibexa:
    system:
        admin_group:
            headless:
                documentation_url: 'https://doc.example.com/headless'

For QA:

Covered by the related PRs: with headless enabled and no preview URL, the Page Builder placeholder and the location View tab link to the configured documentation URL, and hide those links when it is set to ~.

Documentation:

New headless.documentation_url siteaccess setting (URL of the documentation on connecting a front-end application, defaults to the Ibexa documentation).

🤖 Generated with Claude Code

[konradoboza]

Can it be ever null?

[GrabowskiM]

Probably it shouldn't ever (at least I always call it with argument), but that's convention from all other methods in this class

[konradoboza]

I wouldn't call it convention - if we are sure the parameter cannot be null we should skip it. Unless you see a good reason not to. @tbialcz please advice here.

[konradoboza]

Can it be ever null?

[tbialcz]

It can be null on purpose: null means the current siteaccess and it goes straight to ConfigResolver::getParameter() and that's how page-builder and site-context call it

[tbialcz]

Looks good for me.
Could you add a test for documentation_url: ~? It's the only URL with a non-null default, so ~ is the only way to hide the links.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[adriendupuis]

Doc is ready at https://doc.ibexa.co/en/saas/content_management/pages/headless_page_builder/

ibexa/page-builder#629 can target it.
It could specifically target the "Configuration" section but this section will stay on top of page.

[adriendupuis]

Suggested change

	# @todo replace with the headless documentation URL once the page is published
	ibexa.site_access.config.default.headless.documentation_url: 'https://doc.ibexa.co/'
	ibexa.site_access.config.default.headless.documentation_url: 'https://doc.ibexa.co/en/saas/content_management/pages/headless_page_builder/'