Add zig-waybar-contrib package metadata

[erffy]

No description provided.

[github-actions]

🎉 Thanks for contributing to Zig Index!

Your PR to add a new entry to the registry is being reviewed.

📋 Checklist

Please ensure your submission meets our guidelines:

• Project is open source and hosted on GitHub
• Project uses Zig (has build.zig or build.zig.zon)
• JSON file follows the schema (name, owner, repo, description are required)
• Description is under 200 characters
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[github-actions]

✅ Registry Validation: All checks passed!

Check	Status
Schema Validation	✅ Passed
Duplicate Check	✅ Passed
Filename Lint	✅ Passed

🎉 Your submission looks good! A maintainer will review it shortly.

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[muhammad-fiaz]

@erffy Thanks for PR! Now You can Merge the Changes, Before that Make sure all Details and main branch needed to up to date are correct!