Refactor Dockerfile to cache node_modules

[d4mr]

PR-Codex overview

This PR focuses on optimizing the Docker build process for a Node.js application by restructuring the installation of dependencies and separating the production dependencies into a distinct stage.

Detailed summary

• Added python3-pip installation.
• Changed the copying order to first include package.json and yarn.lock for caching.
• Simplified dependency installation by removing the redundant second install step.
• Introduced a new build stage prod-deps for installing only production dependencies.
• Updated the COPY command to pull node_modules from the prod-deps stage instead of the build stage.

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[d4mr]

we want to copy code after we run yarn install. That's how we get benefits from the layer cache. I'll investigate the build errors @jakeloo

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