Announce Divi contact form validation and success states for screen readers

[RichardGeorgeDavis]

Problem

The plugin currently improves labels/required states, but feedback messaging for errors/success still needs explicit screen-reader announcement behavior and keyboard-flow validation.

Proposed scope

• Add explicit aria-live/status semantics for contact form validation and success messages where plugin-managed selectors exist.
• Ensure feedback is programmatically associated with user interaction flow.
• Preserve current label and required-field enhancements.

WCAG-oriented acceptance criteria

• Screen readers announce form errors and success messages without requiring focus hunting.
• Keyboard-only users can complete form flows without losing context when errors appear.
• Color is not the sole cue for validation feedback.
• No regressions in existing contact form accessibility behavior.

Related context

• Related to historical keyboard/form issue Can't select checkbox in Divi contact form with keyboard #60 and broader WCAG roadmap issue Review plugin roadmap against WCAG 2.2 and current assistive technology expectations #102.

[RichardGeorgeDavis]

Work for this issue is currently consolidated into #121. Final closure should happen after packaged-plugin and runtime verification are complete.