Add missing ARIA labels to icon-only buttons

[Mosas2000]

Description

Multiple components have icon-only buttons without aria-label attributes, making them inaccessible to screen reader users.

Affected Components

• ShareModal.tsx - Share buttons
• MobileBottomSheet.tsx - Close button
• AdminRBACDashboard.tsx - Action buttons

Impact

• Violates WCAG 2.1 Level A (1.1.1 Non-text Content)
• Screen reader users cannot understand button purpose
• Fails accessibility audits

Solution

Add descriptive aria-label to all icon-only buttons:

<button aria-label="Share on Twitter">
  <TwitterIcon />
</button>

Priority

♿ HIGH - Accessibility compliance