Pull Request resolves #48243 .

• I read the Generative AI policy and my contribution is either not created with the help of AI or is compatible with the policy and GNU/GPL 2 or later.

Summary of Changes

This PR fixes accessibility issues reported in Issue #48243 where structural and non-standard fields (specifically Spacer and Captcha) generate invalid <label> markup.

Root cause:
These fields were rendering <label> tags that were either missing a for="..." attribute or pointing to a DOM ID that did not exist (since structural elements and JS widgets do not render standard <input id="..."> controls). This triggers "label not associated with a form control" warnings in developer consoles and accessibility testing tools.

Changes:

1. renderlabel.php Layout: Detects if the $for attribute is empty. If it is, it outputs a <span> instead of a <label>, ensuring semantic validity while preserving styling. It also accepts a predefined $id variable instead of enforcing $for . '-lbl'.
2. CaptchaField: Overrides getLabel() to pass an empty string for the for attribute and passes the id explicitly, triggering the new <span> behavior since the JS captcha widget doesn't render a matching input ID.
3. SpacerField: Modifies the hardcoded label string generation to natively output a <span> element instead of a <label>, as spacer fields act strictly as structural dividers.

Testing Instructions

1. Configure a Joomla site with a com_contact menu item.
2. Enable a Captcha plugin (if available) and assign it to the contact form.
3. Navigate to the Contact form on the frontend.
4. Inspect the developer console and run an accessibility checker (e.g. Lighthouse, WAVE, or Axe).

Actual result BEFORE applying this Pull Request

• <label> tags are incorrectly used for elements that are not form controls, causing accessibility validation errors: "A form label must be associated with a control".

Expected result AFTER applying this Pull Request

• No accessibility console errors regarding jform_spacer-lbl or jform_captcha-lbl.
• The visual styling and layout of the spacer and captcha fields remain identical.
• The HTML inspector shows that the "labels" for these elements are now properly rendered as <span> tags rather than invalid <label> tags.

Link to documentations

Please select:

• Documentation link for guide.joomla.org:

• No documentation changes for guide.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed