fix: add openssl to ai-service and fix its DATABASE_URL for Docker

- Dockerfile.ai: install openssl (required by Prisma native engine)
- docker-compose.yml: set DATABASE_URL to postgres:5432 instead of
  localhost, add postgres healthcheck dependency

Co-authored-by: Cursor <cursoragent@cursor.com>

docker-compose.yml

@@ -88,11 +88,13 @@ services:
     restart: unless-stopped
     env_file: .env
     environment:
+      DATABASE_URL: postgresql://postgres:postgres@postgres:5432/coursecraft?schema=public
       REDIS_URL: redis://redis:6379
       REDIS_HOST: redis
       REDIS_PORT: "6379"
       NODE_ENV: production
     depends_on:
+      postgres: { condition: service_healthy }
       redis: { condition: service_healthy }
 
   web:

docker/Dockerfile.ai

@@ -1,5 +1,7 @@
 FROM node:20-slim
 
+RUN apt-get update -y && apt-get install -y openssl && rm -rf /var/lib/apt/lists/*
+
 RUN corepack enable && corepack prepare pnpm@9.0.0 --activate
 
 WORKDIR /app