Add src/placeholder.test.ts to confirm the Vitest harness works end-to-end (npm test passes). Update CLAUDE.md project structure to reflect the now-created src/ directory. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Configures TypeScript with strict: true, target ES2020, rootDir src/, outDir dist/. tsc --noEmit passes cleanly. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>