feat: Add Nixpacks build configuration

[DavidMelamed]

📦 Nixpacks Build Configuration

This PR adds zero-config build system using Nixpacks.

Changes:

• ✅ Add for automatic builds
• ✅ Add health check script
• ✅ Enable deployment to Railway, Render, and other platforms

Benefits:

• 🎯 Zero-config builds that detect your stack
• 🔄 Automatic dependency detection
• 📦 Consistent build environment
• 🚀 Deploy anywhere with one command

Supported Platforms:

• Railway (primary)
• Render
• Google Cloud Run
• Fly.io
• Any Docker-compatible platform

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