Author and correct a usmconfig.json

For: Adopter

The adopter-onboarding loop the config exists for: init writes a config, the consumer tunes output paths, and a typo fails loudly instead of silently misdirecting output.

Part of: config-validation

Steps

• Edit (spec) — usmconfig.json outputs section with repo-specific paths
• Check (cli) — usm validate --config usmconfig.json before wiring it into CI
• Fix (spec) — any reported key — unknown keys list the supported set; renamed keys show the modern name
• Run (cli) — usm generate with the corrected config and confirm outputs land in the configured paths

How this is verified

• exit 0, structured report, no side effects on any file
• exit 1 with same errors as load-time validation for an invalid config