Set up USM in a new repo

For: Adopter

First-run experience: an adopter initializes USM in their repository and reviews the generated usmconfig.json without reading docs first.

Part of: Init Command

Steps

• Run (cli) — usm init in the repo root
• Review (cli) — generated usmconfig.json — services match apps/*, shared and data paths detected correctly
• Correct (spec) — any misdetected services or missing shared packages by editing usmconfig.json before running usm scan

How this is verified

• usmconfig.json created with services matching apps/*
• exit code 0