docker: ensure npm global CLIs are on PATH in image build

[SFangYy]

Description

ensure npm global CLIs are on PATH in image build

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

docker build -f Dockerfile -t localhost/picker:latest

Checklist:

• My code follows the style guidelines of this project
• I have added the appropriate labels
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[Copilot]

Pull request overview

This PR adjusts the Docker image build so that Node installed via nvm exposes globally installed npm CLI executables on PATH, improving usability of npm global tools inside the built image.

Changes:

• Moves the nvm/Node installation step later in the Dockerfile (after building/installing Picker).
• Adds a current symlink for the active Node version and prepends its bin/ directory to PATH so global npm CLIs resolve correctly.
• Keeps /usr/local/bin symlinks for node, npm, and npx.

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