Wire frontend into Docker Compose with type-safe API client

- Add frontend service to docker-compose.yml (port 3000, BACKEND_URL env var)
- Add frontend/Dockerfile using adapter-node for plain Node/Docker runtime
- Switch svelte.config.js from adapter-auto to adapter-node
- Generate OpenAPI types from backend spec (openapi-typescript + openapi-fetch)
- Add src/lib/server/api.ts as server-only typed API client factory
- Add generate:api script to regenerate types when backend spec changes

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -32,5 +32,17 @@ services:
       db:
         condition: service_healthy
 
+  frontend:
+    build:
+      context: ./frontend
+      dockerfile: Dockerfile
+    container_name: mealprep-frontend
+    ports:
+      - "3000:3000"
+    environment:
+      BACKEND_URL: http://app:8080
+    depends_on:
+      - app
+
 volumes:
   pgdata: