Receipt accounting: parse gpu_sku/gpu_seconds/cost_usd into the run ledger; surface in run status

[aarontrowbridge]

Important

Problem — Warrants and the campaign fold can't see GPU spend: the run ledger debits nothing when a cloud run burns GPU-hours, because receipts are never parsed for gpu_sku/gpu_seconds/cost_usd. Spend that isn't recorded can't be gated (the GPU-plane invariant).

Acceptance Criteria

• The run-ledger record gains optional GPU fields (gpu_sku, gpu_seconds, cost_usd), schema-versioned
• Remote run completion parses them out of the receipt/run-dir into the ledger row
• amico ledger query / run status surface them
• FakeCloud fixture extended to emit the fields; tests pin the parse (buildable NOW against fixtures — field names per the runner contract, adjusted if the cloud names differ)

Design-of-record: vault spec spec-20260818-gpu-plane (ladder item 2). Soft-blocked on the cloud runner contract landing; the client half doesn't need to wait.