agents-md does not detect version properly if ranges are used

Link to the code that reproduces this issue

https://codesandbox.io/p/sandbox/optimistic-star-2nq57m

To Reproduce

Run npx @next/codemod@canary agents-md --output AGENTS.md in a repo with a range provided for next.

Current vs. Expected behavior

If I run npx @next/codemod@canary agents-md --output AGENTS.md in a repo using ^16 for next, the code detects version 16 and tries to download it, which is both incorrect and does not work:

$ npx @next/codemod@canary agents-md --output AGENTS.md

Downloading Next.js 16 documentation to .next-docs...
Failed to pull docs: Could not find documentation for Next.js v16. This version may not exist on GitHub yet.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #12-Ubuntu SMP PREEMPT_DYNAMIC Fri Jan  9 20:46:52 UTC 2026
  Available memory (MB): 31021
  Available CPU cores: 22
Binaries:
  Node: 24.12.0
  npm: 11.6.2
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 16.1.6 // Latest available version is detected (16.1.6).
  eslint-config-next: N/A
  react: 19.2.4
  react-dom: 19.2.4
  typescript: 5.9.3
Next.js Config:
  output: standalone

Which area(s) are affected? (Select all that apply)

Not sure

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

No response

Start with the linked CodeSandbox and run the agents-md codemod in a repository whose Next.js dependency is specified as ^16. Trace the version-detection entry point used by npx @next/codemod@canary agents-md; done means a range does not trigger a download for an unsupported exact version and the command can generate AGENTS.md successfully.