Fixes SQLSTATE[42P07] duplicate-table failures when multiple app
environments share one NightOwl database: migration history now lives in
the nightowl DB (idempotent across environments) instead of each app's
primary DB. Adds baseline reconciliation that adopts an existing schema
regardless of where its history currently lives, a startup schema-drift
warning, and flips NIGHTOWL_RUN_MIGRATIONS to default false.
nightowl:install delegates to nightowl:migrate.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>