Returns every pipeline spend policy row on this node: the node-wide cap
(node), the per-user default (default), and any per-user overrides.

These are separate from the LLM quotas at /user-quotas, and have
different default semantics: an axis with no policy row is UNLIMITED,
whereas LLM axes fall back to a small platform safety cap. Pipeline
compute runs in the node owner's own AWS account, so capping is opt-in
per node rather than a platform default.

Permissions: Node owner or workspace administrator on public accounts.