bbea3f4473
Adds scripts/migrate-mystery-content.ts which reads rooms, items,
encounters, and endings from TypeScript source and emits byte-identical
markdown files under src/mystery/world/{rooms,items,encounters,endings}/.
Installs tsx as a devDep to support .ts imports across src/ during the
one-shot run.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>