build: add CloudFront cache invalidation to the release action

[brettflorio]

Resolves #234

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✅ brettflorio
❌ Brett Florio

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[Copilot]

Pull request overview

This PR adds CloudFront cache invalidation to the release workflow to ensure that updated CDN content is immediately available to users after deployment.

Changes:

• Added a new step to invalidate CloudFront cache after S3 CDN deployment
• Configured AWS credentials using existing CDN secrets for CloudFront CLI access

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