mx-migration-author

Author and review Drizzle SQL migrations safely for rolling deploys. Triggers when editing apps/core/src/database/schema/*.ts or apps/core/src/database/migrations/*.sql, when the user runs drizzle-kit generate, when "lint-migrations" reports a violation, or on prompts like "迁移", "改 schema", "alter table", "add a column", "drop column", "migration safety". Enforces the expand-contract pattern because mx-core ships…