add aria-labels to icon buttons

[zcesur]

💡 What: Added ARIA labels to icon-only buttons across multiple live components (bounty_live.ex, contract/view_live.ex, contract_live.ex, org/dashboard_live.ex).
🎯 Why: To ensure screen reader accessibility. Buttons that contain only an icon and no text need an explicit aria-label for screen reader users to understand their purpose.
♿ Accessibility: Improved screen reader accessibility for various actions like sending messages, editing, and opening menus.

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PR created automatically by Jules for task 14605475153828946619 started by @zcesur

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