feat: Integrate APM (Agent Package Manager) into Squad CLI for skill portability #824

Summary

Integrate APM (Agent Package Manager, github.com/microsoft/apm) into Squad CLI so that squad init generates an apm.yml file, making skills versioned, portable, and community-shareable.

Context

From tamirdresher_microsoft/tamresearch1#2135 — Seven's research concluded that Squad already IS context engineering (charters, history.md, decisions.md, skills, routing are context primitives). APM adds value for the upstream Squad CLI by providing package.json-style skill management.

What is APM?

APM is basically package.json for AI agent context. You declare skills, instructions, and prompts in apm.yml and apm install deploys them to .github/, .claude/, .cursor/ etc.

Recommendation

• Don't adopt APM wholesale for existing Squad repos (.squad/ already does what APM does)
• DO integrate APM into the CLI so squad init generates apm.yml
• This fits naturally into the plugin/marketplace story
• Skills become versioned, portable, and community-shareable via APM registry

Implementation Ideas

1. squad init generates apm.yml alongside .squad/
2. squad skill publish exports a skill to APM format
3. squad skill install <name> pulls from APM registry into .squad/skills/
4. Skill marketplace browsing uses APM registry as a source

Origin

Seven's full analysis: tamirdresher_microsoft/tamresearch1 .squad/research/2116-context-engineering-20260404.md