[DOCS] Dockerfile uses npm for install instead of native installer

Documentation Type

Missing documentation (feature not documented)

Documentation Location

https://code.claude.com/docs/en/devcontainer

Section/Topic

Getting started in 4 steps

Current Documentation

The docs for setting up in docker currently say "Clone the Claude Code reference implementation repository"

What's Wrong or Missing?

The Dockerfile in the reference implementation repo uses npm to install claude: RUN npm install -g @anthropic-ai/claude-code@${CLAUDE_CODE_VERSION}

However, the main installation docs recommend a "Native Install", and npm is no longer recommended. When you launch claude code after installing with npm, the CLI says that you should switch to the native installer, so the reference implementation is recommended an outdated approach.

Suggested Improvement

Update the Dockerfile to use the native install approach.

Impact

High - Prevents users from using a feature

Additional Context

_No response_