Lafeitu Agent Interface

# 1. Search for items
curl https://lafeitu.cn/api/v1/products?q=rabbit

# 2. Add to cart (Auth Required)
curl -X POST https://lafeitu.cn/api/v1/cart \
  -H "X-User-Account: user@example.com" \
  -H "X-User-Password: secret" \
  -H "Content-Type: application/json" \
  -d '{"product_slug": "lengchitu", "gram": 200, "quantity": 2}'

Base URL: https://lafeitu.cn/api/v1

# 1. CORE PRINCIPLES
- **Stateless**: No cookies. Verify identity via headers on every request.
- **Idempotent**: Retry safe.
- **JSON-First**: Always send 'Content-Type: application/json'.

# 2. AUTHENTICATION (Headers)
REQUIRED for all Cart/Order operations.
- X-User-Account:  <mobile_or_email>
- X-User-Password: <raw_password>

# 3. ENDPOINTS

## Product Catalog (Public)
GET /products
    ?q={keyword}       Search products
    ?category={cat}    Filter by category

## Shopping Cart (Auth Required)
GET    /cart          View current cart state
POST   /cart          Add item (Cumulative)
       Body: { product_slug, gram, quantity }
PUT    /cart          Set item quantity (Absolute)
       Body: { product_slug, gram, quantity }
DELETE /cart          Remove item
       Body: { product_slug, gram }

## User Profile (Auth Required)
GET    /user/profile  Get user details & points