🎨 Palette: [Accessibility] Add ARIA labels to icon-only buttons

[secrooq]

💡 What: Added aria-label attributes to icon-only buttons and links across several components (RelayDashboard, VaultDashboard, AdminDashboard, SecretReader).

🎯 Why: To improve accessibility for users relying on screen readers. Previously, these elements only had title attributes, which are not reliably announced by all assistive technologies.

📸 Before/After: No visual changes. Screen readers will now announce "Delete Custom Domain Suffix", "Copy", "Delete Permanently", "Refresh index", "Clear Console", and "Download file" when interacting with these buttons.

♿ Accessibility: Enhances screen reader support by providing explicit labels for interactive elements that lack text content.

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PR created automatically by Jules for task 17940563795564704351 started by @secrooq

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