feat(output): add --show-gpu-ratios (vCPU/GPU, RAM/GPU columns)

[scttfrdmn]

Summary

find/search show vCPUs and GPUs as separate columns, so seeing whether an instance can actually feed its accelerators requires computing vCPU/GPU by hand across two columns. For CPU/IO-bound ML workloads (data prep or I/O-heavy inference where the GPU sits mostly idle) that ratio is the decisive spec, not the raw GPU count — the issue's own motivating example: g5.4xlarge (16 vCPU / 1 GPU = 16.0) vs g5.12xlarge (48 vCPU / 4 GPUs = 12.0). The naive "4 GPUs → 4x throughput" reading of the separate columns is backwards: the bigger box actually starves each GPU more.

Adds TableOptions.ShowGPURatios, wired to a new --show-gpu-ratios flag on both find and search. Renders two additional columns (vCPU/GPU, RAM/GPU) alongside the existing GPUs/GPU Model/VRAM columns, computed from data already present in InstanceTypeResult — no new API calls. A fractional GPU (GPUs==0, GPUPartitionSize>0, e.g. g6f.large — a time-sliced L4 partition) renders - for both rather than dividing by a fractional count: that row is a shared slice of one GPU, not a caller-controlled resource-feeding ratio, so the number would look precise but answer no real question.

Verification against live AWS

us-east-1, --show-price --show-gpu-ratios:

g5.4xlarge   → vCPU/GPU 16.0, RAM/GPU 64.0   (matches the issue's own table exactly)
g5.12xlarge  → vCPU/GPU 12.0, RAM/GPU 48.0   (matches the issue's own table exactly)
g6f.large    → vCPU/GPU  -,   RAM/GPU  -     (fractional GPU, correctly dashed)

Test plan

• New tests in pkg/output/printer_test.go: TestPrintTable_ShowGPURatios_MotivatingExample (reproduces the issue's own g5.4xlarge/g5.12xlarge numbers), TestPrintTable_ShowGPURatios_RAMPerGPU, TestPrintTable_ShowGPURatios_FractionalGPUShowsDash, TestPrintTable_ShowGPURatios_NonGPURowShowsDash, TestGPURatioDisplay (pure-helper boundary cases: zero memory, zero GPUs), TestPrintTable_ShowGPURatios_Default (columns are opt-in — absent without the flag).
• Confirmed regression: stashing pkg/output/printer.go makes go vet fail to compile the new tests (unknown field ShowGPURatios) — the tests cannot pass without the fix.
• go build ./..., go vet ./..., go test ./... all green
• golangci-lint run ./cmd/... ./pkg/output/... — only pre-existing findings in untouched code (app.go, gendocs.go, root.go, and one unrelated printer.go helper), none in the new code
• make check-docs clean (regenerated docs-gen/find.md and docs-gen/search.md for the new flag)
• CHANGELOG.md updated under ## [Unreleased]

Fixes #51

[codecov]

Codecov Report

❌ Patch coverage is 90.90909% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cmd/find.go	66.66%	1 Missing ⚠️
cmd/search.go	50.00%	1 Missing ⚠️

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