Clear and concise description of the problem

The supported package managers allow for the installation of only production dependencies. This is usually motivated by a desire for a smaller deployment footprint.

Since ni already supports the "mirror" -D flag for installing only development dependencies, I propose adding the -P flag for installing only production dependencies.

Suggested solution

I suggest adding the -P flag to the ni command, which should instruct agents to install only production dependencies (as defined by the agent). I am happy to provide a PR for it.

Alternative

No response

Additional context

There are two things worth pointing out, and they may both trigger a change in antfu-collective/package-manager-detector.

• Ideally, I'd like to combine clean install (nci a.k.a. ni --frozen) with -P flag, but that would require a change frozen command in antfu-collective/package-manager-detector to accept a parameter. This is my ultimate motivation for the change.
• New versions of npm have deprecated --production flag, and will print a warning suggesting using --omit=dev. My current PR uses the new (--omit=dev) flag. If we want to support --production flag for older versions (I believe v6 and prior) of npm that do not support --omit we would need to make a change in antfu-collective/package-manager-detector to support that.

If you're up for making these changes, I'd happily provide PRs for them.

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.