Choose AI Provider & Integrate SDK #95

Scope: Decide on LLM provider (OpenAI, Anthropic, Gemini, etc.), add the SDK dependency to apps/api, configure the API key via env, and create a shared AI client utility.

Files involved: apps/api/, packages/types/

Checklist:

• Research & pick provider (cost, latency, JSON mode support, structured output)
• Add provider SDK to apps/api dependencies
• Add AI_API_KEY / AI_PROVIDER env vars and validate in apps/api/src/lib/env.ts [ locally or shared we can figure it out]
• Create apps/api/src/lib/ai/client.ts — thin wrapper around the provider SDK
• Document the chosen provider and setup steps