feat(packages): add declarative npm package installation via chezmoi

[fx]

Summary

• Implements declarative npm package installation using chezmoi's data-driven approach
• Adds @anthropic-ai/claude-code package to the default installation
• Updates chezmoi-development skill documentation with package installation patterns
• Adds comprehensive test coverage for npm package installation

Implementation

New Files:

• .chezmoidata/packages.yaml - Declares npm packages to install
• .chezmoiscripts/run_onchange_after_install-npm-packages.sh.tmpl - Installation script that runs when package list changes

Modified Files:

• .claude/skills/chezmoi-development/SKILL.md - Added "Declarative Package Installation" section with npm example
• test/verify-marketplace.sh - Added npm package verification
• test/test-coder-existing.sh - Fixed test to use valid JSON in mock settings file

Key Features

1. Data-Driven: Package declarations in YAML file separate from installation logic
2. Change Detection: Uses run_onchange_ prefix so script only runs when package list changes
3. Idempotent: Checks if packages are already installed before attempting installation
4. Mise Integration: Uses mise exec to ensure npm commands work in mise-managed Node.js environment
5. Extensible: Pattern easily adaptable to other package managers (apt, brew, pip)

Testing

All tests pass:

• ✅ Non-Coder environment (fresh install)
• ✅ Coder fresh install (with /shared/ seeding)
• ✅ Coder existing ~/.claude (preserves user files)

Each test verifies:

• Marketplace configuration
• NPM package installation (@anthropic-ai/claude-code)

Documentation

Updated the chezmoi-development skill with comprehensive documentation:

• Pattern explanation
• Complete working example
• Template variable naming conventions
• Adaptability to other package managers

[Copilot]

Pull Request Overview

This PR adds declarative npm package installation to the chezmoi dotfiles setup. It introduces a new pattern for managing npm global packages through YAML configuration, automatically installing them when the package list changes.

• Adds .chezmoidata/packages.yaml to declare npm packages
• Creates run_onchange_after_install-npm-packages.sh.tmpl script for automatic installation
• Extends test verification to check npm package installation

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
.chezmoidata/packages.yaml	New YAML file declaring npm global packages (e.g., @anthropic-ai/claude-code)
.chezmoiscripts/run_onchange_after_install-npm-packages.sh.tmpl	New script that installs npm packages when package list changes, with mise integration
test/verify-marketplace.sh	Extended to verify npm package installation, supports both yq-based parsing and fallback
test/test-coder-existing.sh	Updated test fixture to use valid JSON instead of plain text
.claude/skills/chezmoi-development/SKILL.md	Added documentation for the declarative package installation pattern