feat(search): add gpu-search command to find GPU instance types

[theFong]

Summary

Add brev search command (aliases: gpu-search, gpu, gpus) to search and filter available GPU instance types across cloud providers.

Features

• Filter by GPU name, provider, VRAM, compute capability, disk size, boot time
• Sort by price, vram, boot-time, gpu-count, etc.
• Show instance features (stoppable, rebootable, flex-ports)
• JSON output support for scripting
• Pipeable output for chaining with other commands

Examples

# Search all GPUs sorted by price
brev search

# Filter by GPU name
brev search --gpu-name A100

# Filter by specs
brev search --min-vram 40 --max-boot-time 5 --sort price

# JSON output for scripting
brev search --json | jq '.[] | select(.price < 2)'

# Pipe to create
brev search --gpu-name A100 | brev create my-instance

Test plan

• brev search shows available GPUs
• Filters work correctly (--gpu-name, --min-vram, etc.)
• Sort options work (--sort price, --sort vram)
• JSON output is valid JSON
• Piped output works with downstream commands

[theFong]

Manual QA Results ✅

Build & Static Analysis:

• ✅ Build passes
• ✅ go vet passes
• ✅ Unit tests pass (36.7% coverage on gpusearch package)

Test Plan Verification:

• ✅ brev search shows available GPUs - Verified: Returns full table of GPU instances sorted by price
• ✅ Filters work correctly - Verified: --gpu-name A100, --min-vram 40, --sort price all work as expected
• ✅ Sort options work - Verified: Sorting by price shows cheapest first
• ✅ JSON output is valid JSON - Verified: --json outputs valid JSON array
• ✅ Piped output works with downstream commands - Verified: brev search | brev create successfully creates instance

Notes:

• Comprehensive unit tests cover all filter and sort functionality
• Pre-existing test failures on main (Darwin platform tests, Docker daemon) are unrelated to this PR

[tylerfong]

Fire