Plugin install fails inside Docker/devcontainer due to SSH authentication

## Description

`claude plugin install` fails when running inside a Docker container (e.g., VS Code devcontainer) because the git clone uses SSH (`git@github.com:`) and the container typically doesn't have SSH keys configured.

## Steps to reproduce

1. Open a project inside a devcontainer (Docker)
2. Add a marketplace:
```bash
claude plugin marketplace add addyosmani/agent-skills
```
3. Try to install a plugin:
```bash
claude plugin install agent-skills@addy-agent-skills
```

## Expected behavior

The plugin installs successfully (as it does outside the container).

## Actual behavior

```
Installing plugin "agent-skills@addy-agent-skills"...
✘ Failed to install plugin "agent-skills@addy-agent-skills": Failed to clone repository:
Cloning into '/home/vscode/.claude/plugins/cache/temp_github_...'...
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.
```

## Workaround

Configure git to use HTTPS instead of SSH:

```bash
git config --global url."https://github.com/".insteadOf "git@github.com:"
```

## Suggested fix

Consider using HTTPS (`https://github.com/`) as the default clone method for public marketplace repositories, or fall back to HTTPS when SSH fails. Public repositories don't require SSH authentication, so HTTPS would work without any credentials.

## Environment

- **Claude Code version:** 2.1.110
- **OS:** Linux (Docker container / devcontainer)
- **Shell:** bash

## Contributing

I'd be happy to submit a PR for this if the team is interested. Let me know!