feat: add fresh copy success toast for badge markdown

[codedbydollys10]

Summary

Added a toast/snackbar notification when badge markdown is copied from the Badge Section.

Closes #160

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Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup

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Changes Made

• Added a success toast notification for badge markdown copy actions
• Toast appears at the bottom of the screen after a successful clipboard write
• Toast automatically dismisses after approximately 2000ms
• Added accessibility support with role="status" and aria-live="polite"
• Preserved the existing inline ✓ Copied! button state
• Ensured functionality works for all badge copy actions (streak, commits, combined)

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How to Test

1. Navigate to the Badge Section

2. Click the Streak badge copy button

3. Verify:

   • Badge markdown is copied to the clipboard
   • Existing ✓ Copied! button state still appears
   • Toast appears at the bottom of the screen

4. Wait ~2 seconds and confirm the toast disappears

5. Repeat for:

   • Commits badge copy button
   • Combined badge copy button

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Screenshots (if UI change)

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Checklist

• Linked issue in summary
• Self-reviewed the diff
• No unrelated files modified
• Existing functionality preserved
• Added/updated tests if applicable

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Accessibility Checklist

• role="status" added
• aria-live="polite" added
• Keyboard interaction remains unchanged
• Existing UI behavior preserved

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Additional Notes

Implementation was intentionally limited to src/components/BadgeSection.tsx to keep the change focused and minimize merge conflict risk.

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[codedbydollys10]

Hello @Priyanshu-byte-coder
Apologies for the duplicate PR on the same issue. My previous PR kept running into recurring merge conflicts even after multiple resolutions, so I started fresh from an updated branch and recreated the fix to keep the changes clean and conflict-free. Thanks for your understanding.

The failing Playwright test appears unrelated to this change.

This PR only modifies src/components/BadgeSection.tsx to add a toast notification after successful badge markdown copy actions.

The CI failure occurs in e2e/dashboard-widgets.spec.js where getByRole('heading', { name: 'Goals' }) matches both "Goals & Insights" and "Goals", causing a strict mode violation. This appears to be an existing dashboard test issue and is outside the scope of the badge toast implementation.