Plugin marketplace clones via SSH (git@github.com) instead of HTTPS, failing even for public repos

Bug Description

When running /plugin marketplace add <user/repo>, Claude Code attempts to clone the repository using SSH (git@github.com:) instead of HTTPS. This causes the command to fail even for public repositories if the user has no SSH keys configured.

Steps to Reproduce

1. Run /plugin marketplace add sunmerrr/claude-pipeline (a public repo)
2. Observe failure:

Error: Failed to clone marketplace repository: SSH authentication failed.

Cloning into '...'...
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Expected Behavior

Public repositories should be cloned via HTTPS — no authentication required:

git clone https://github.com/sunmerrr/claude-pipeline

Actual Behavior

Clones via SSH regardless of repo visibility:

git clone git@github.com:sunmerrr/claude-pipeline

Environment

• Claude Code version: 2.1.92
• OS: macOS (arm64)
• gh CLI protocol is already set to https — only the plugin system uses SSH

Notes

This appears to be a hardcoded SSH URL in the plugin system internals. Switching to HTTPS for public repos (or respecting the user's gh CLI protocol setting) would fix this.