curl https://zeplo.ai/api/contacts/5 \
  -H "Cookie: connect.sid=s%3A7HImZ-T2BxWSbUsf9dtWdOlBW4rVuORO.5J0Do0NyvBu%2BkTvu1aHvtNs00BKhkpUKTwiokLS0cpw"

{
  "success": true,
  "data": {
    "id": 5,
    "name": "John Doe",
    "phone": "919876543210",
    "email": "john@example.com",
    "avatar": null,
    "tags": ["vip", "customer"],
    "groups": [
      { "id": 1, "name": "Customers" },
      { "id": 3, "name": "VIP" }
    ],
    "metadata": {
      "company": "Acme Inc"
    },
    "lastMessageAt": "2026-01-15T10:30:00Z",
    "conversationCount": 3,
    "messageCount": 42,
    "createdAt": "2026-01-01T08:00:00Z",
    "updatedAt": "2026-01-15T10:30:00Z"
  }
}