feat: remove a11y for blocks (added by beapi accessibility plugin)

[cedric07]

Clean des fichiers de fix A11y, qui sont maintenant géré via le plugin beapi accessibility

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Note

Low Risk
Low risk: this removes two small DOM-manipulation helpers and their imports; risk is limited to potential regression if the external accessibility plugin is not present or behaves differently.

Overview
Removes the custom JS a11y fixes for WP blocks by deleting ImageBlock (figure role/aria-label on image captions) and TableBlock (adds scope="col" to table headers).

Updates src/js/index.js to no longer import/init these modules, relying on the external accessibility plugin instead.

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