feat(tools): add Rush monorepo support

[clanzhang]

Description

Closes #139

Add support for Rush monorepos by detecting
rush.json and using rush-pnpm as the executable in the pnpm agent.

How it works

Rush provides rush-pnpm — a transparent wrapper around the user's
pnpm binary that configures it to work within the Rush monorepo.
Since rush-pnpm accepts the same CLI arguments as pnpm, we only
need to swap the executable.

Detection strategy:

1. Before falling back to package-manager-detector, check for
   rush.json by traversing up from cwd.
2. If found, set options.rush = true and return 'pnpm' as the agent.
3. The pnpm agent reads options.rush and uses rush-pnpm instead of pnpm.

Changes

• types/base.ts — Add optional rush?: boolean to BaseOptions
• utils/rush.ts — New module: isRushMonorepo() and findRushRoot()
• agent-entry/detect.ts — Pre-check for Rush before package-manager-detector
• agents/pnpm/list.ts — Resolve executable dynamically via resolveExecutable()

Notes

• rush-pnpm is CLI-compatible with pnpm, so pnpm ls, pnpm root, etc.
  work identically. No argument construction logic changes.
• getCatalogs() returns {} automatically for Rush projects since they
  don't have pnpm-workspace.yaml.
• No new dependency is introduced.

Validations

• Follow our Code of Conduct
• Read the Contributing Guide
• Check that there isn't already a PR that addresses the same issue

[antfu]

Would you like to contribute to package-manager-detector first to make this more generic? Thanks

[clanzhang]

Would you like to contribute to package-manager-detector first to make this more generic? Thanks

Sure! I'll contribute to package-manager-detector first to add Rush support there.

One question before I start: currently detect() returns the package manager name as a string. For Rush, we need to signal both "this is pnpm" and "use rush-pnpm as the executable". Would you prefer:

A separate export like getAgent() that returns both the package manager and the resolved executable name?
Or extend the return type to include an optional executable field?
Happy to go with whichever approach you think fits best.

[antfu]

Maybe we could have pnpm-rush type, that inherits things from pnpm. And after package-manager-detector gets released, in node-modules-inspector we would accept both pnpm and pnpm-rush as supported agents.

[clanzhang]

Maybe we could have pnpm-rush type, that inherits things from pnpm. And after package-manager-detector gets released, in node-modules-inspector we would accept both pnpm and pnpm-rush as supported agents.

Hi @antfu, I've opened a PR on package-manager-detector as you suggested:

antfu-collective/package-manager-detector#75

Added pnpm-rush as a new agent type inheriting from pnpm, with rush-pnpm as the executable. Rush detection is done via rush.json in the directory traversal, following the same pattern as yarn/yarn@berry.

Once it's released, I'll update the node-modules-inspector PR to consume the new version. Let me know if anything needs to be adjusted.