Document installer env variables

[TheAlexLichter]

Documentation is

• Missing
• Outdated
• Confusing
• Not sure

Explain in Detail

None of the env variables like VP_HOME or VP_VERSION are documented

Your Suggestion for Changes

Document them

Relevant Page

vite-plus/packages/cli/install.sh

Lines 9 to 14 in f3a3374

	# VP_VERSION - Version to install (default: latest)
	# VP_HOME - Installation directory (default: ~/.vite-plus)
	# NPM_CONFIG_REGISTRY - Custom npm registry URL (default: https://registry.npmjs.org)
	# VP_NODE_MANAGER - Set to "yes" or "no" to skip interactive prompt (for CI/devcontainers)
	# VP_LOCAL_TGZ - Path to local vite-plus.tgz (for development/testing)
	# VP_PR_VERSION - PR number or commit SHA to install from pkg.pr.new

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