Week 3 in-class: MongoDB + Vitest

Synced from si-679-f-26-week03-nyt-jessicadonoho/. These are copies; the original folder is untouched.

• package.json
• SETUP.md
• tsconfig.json
• vitest.config.ts
• src/__tests__/products.test.ts
• src/app.ts
• src/db-explore.ts
• src/db.ts
• src/index.ts
• src/product-router.ts