Add H200 and B200 support for Crusoe provider

[peterschmidt85]

Summary

Crusoe now exposes H200, B200, and GB200 instance types via the API. This PR adds support for H200 and B200 to the Crusoe provider.

• H200: $4.29/GPU-hr (from Crusoe pricing page)
• B200: $7.25/GPU-hr (estimated from B200/H100 ratio on other providers)
• GB200 and MI355X: mapped but no pricing yet -- offers will be skipped until pricing is available
• GB200 uses ARM CPU -- added cpu_arch detection from the API's cpu_type field
• Added GB200 to KNOWN_NVIDIA_GPUS, MI355X to KNOWN_AMD_GPUS (CDNA4)