[FEATURE] Install "category" in marketplace

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The field category can be specified for each plugin in a marketplace. However, it's just metadata, it doesn't have any use, yet.

It could be used to allow us to install the plugins of a whole category with a single command, instead of needing to install one by one or creating custom scripts that iterate the marketplace.

Proposed Solution

Something like claude plugin install --category my-skills --marketplace example or claude plugin install my-skills@example where my-skills is the name of the category.

Alternative Solutions

_No response_

Priority

High - Significant impact on productivity

Feature Category

CLI commands and flags

Use Case Example

A Platform team provides skills for different purposes, for example, Terraform, GitHub Actions, AWS/Boto3 operations, etc.

A developer only interested in the Terraform skills would just install that category and no more.

Likewise, assume there are 50 plugins per category, the current approach is to install one by one (or develop a custom script for that). That's a very tedious approach. There should be a native solution to streamline this operation.

Additional Context

_No response_