Marketplace plugin cloning should default to HTTPS instead of SSH

Problem

When installing a marketplace plugin via /plugin marketplace add owner/repo, Claude Code clones the repository using SSH (git@github.com:...). This fails for users who don't have SSH keys configured for GitHub:

Error: Failed to clone marketplace repository: SSH authentication failed. Please ensure your
SSH keys are configured for GitHub, or use an HTTPS URL instead.

Original error: Cloning into '/Users/user/.claude/plugins/marketplaces/owner-repo'...
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Why this is a problem

• Marketplace repositories are public and read-only — SSH authentication is unnecessary.
• HTTPS works out of the box with no configuration for public repos.
• Many users don't have SSH keys set up for GitHub, especially on fresh machines or if they primarily use HTTPS for their own repos.
• Most tools that clone public repos default to HTTPS for this reason (e.g., go get, cargo install, npm install from git URLs).

Current workaround

Users must either:

1. Set up SSH keys for GitHub, or
2. Configure Git globally to rewrite SSH to HTTPS: git config --global url."https://github.com/".insteadOf git@github.com:

Both are unnecessary friction for a read-only clone of a public repo.

Suggested fix

Default to HTTPS (https://github.com/owner/repo.git) when cloning marketplace repositories. SSH could optionally be supported via a flag or configuration for users behind corporate proxies that block HTTPS but allow SSH.