Alternative cloud provider price comparison (Lambda Labs, CoreWeave)

[maksimov]

Show what the same GPU workload would cost on alternative providers.

In 2026, Lambda Labs and CoreWeave are consistently 40-60% cheaper than
AWS for equivalent NVIDIA hardware. Showing this in the CLI output is a
high-value insight.

• Add pricing data for Lambda Labs, CoreWeave, and other GPU clouds
• Map AWS instance types to equivalent offerings on each provider
• Show in gpuaudit pricing output
• Optionally include in scan recommendations: "This workload costs $X/mo
  on AWS, would cost $Y/mo on Lambda Labs"

Note: extends existing cross-cloud comparison issue (#10) but focused
specifically on GPU-specialist clouds, not just GCP/Azure.