User

{
    "id": 1,
    "email": "user@example.com",
    "api_key": "a1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6",
    "balance_usd": 25.5,
    "total_topups_usd": 100,
    "api_tier": "basic",
    "api_tier_limits": {
        "per_minute": 10,
        "per_day": 2000,
        "max_topups": 100
    },
    "created_at": "2024-01-01T00:00:00Z",
    "updated_at": "2024-01-15T10:30:00Z"
}