Connectors a11y list structure

[pranvinit]

What?

Closes #77650

Adds an accessible list wrapper around connector cards on the Settings > Connectors screen.

Why?

Connector cards render as role="listitem", so they need a valid role="list" parent for correct ARIA structure.

How?

Filters renderable connectors first, renders them inside a named role="list" container, and keeps the AI plugin callout outside the list.

Testing Instructions

1. Go to Settings > Connectors.
2. Inspect the connector cards in DevTools.
3. Confirm the cards are listitems inside the “Available connectors” list.

Testing Instructions for Keyboard

No keyboard interaction changes.

Screenshots or screencast

N/A

Use of AI Tools

Used ChatGPT/Codex to help implement and test the change. Reviewed before submission.

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Co-authored-by: pranvinit <pranavyeole@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>
Co-authored-by: hi0001234d <emptyopssphere@git.wordpress.org>

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