feat(init): bridge to APM during init for cross-team distribution

[danielmeppiel]

Summary

When agentrc init finishes generating instructions, it should detect APM (Agent Package Manager) and offer to initialize it — enabling developers to distribute their agentrc-generated instructions across teams via apm install.

Motivation

agentrc generates high-quality, repo-aware instructions. APM distributes them. Today, going from "I have instructions" to "my org can install them" requires manually creating apm.yml — a step most developers skip because they do not know about APM or how to set it up.

agentrc init is the natural place to bridge this gap: it already runs interactive prompts (via @inquirer/prompts) and calls out to external tools (git, GitHub API). Adding APM detection follows the same pattern.

Behavior

APM state	Interactive mode	--yes / headless
apm in PATH + no apm.yml	Prompt: "Initialize APM for cross-team distribution? (Y/n)" → runs apm init --yes	Skip
apm in PATH + apm.yml exists	Skip	Skip
apm not in PATH	Tip: "💡 Install APM to distribute instructions across your org. See: https://github.com/microsoft/apm"	Skip (respects --quiet)

Design principles

• Delegation, not duplication: agentrc never writes apm.yml — it shells out to apm init --yes. APM owns its manifest.
• Explicit opt-in: the prompt defaults to No. --yes skips it entirely.
• No new I/O paradigm: init already uses @inquirer/prompts and respects --yes/--quiet/--json.
• Graceful degradation: when APM is not installed, a single tip line (respecting --quiet) is the only change.

Implementation

Single file change: src/commands/init.ts — add APM detection and conditional prompt/tip after the generation phase.