v0.4.0 — Correct node detail decoding (NodeDetail)

Fixed

• NodesResource.Find now decodes the real GET /nodes/:id response. That
  endpoint uses a different JSON envelope than GET /nodes (system block nested
  under data, memory as total_memory/free_memory, agent version as
  data.version), so decoding it into Node silently zeroed CPU, RAM, disk,
  GPU, uptime, and agent-version fields. Verified against the live API (node 65).

Changed

• Breaking: NodesResource.Find now returns *NodeDetail instead of
  *Node. NodeDetail faithfully models the detail envelope and adds
  reliability, account_id, and richer location/memory fields. Node prices
  are not part of this endpoint — use NodesResource.List for pricing.