/reload-plugins should re-fetch plugin cache from remote

Problem

/reload-plugins re-reads the local plugin cache but does not re-fetch from the remote source (GitHub repo). This means changes pushed to a marketplace repo are invisible until the user manually deletes the cache directory:

rm -rf ~/.claude/plugins/cache/<marketplace>/<plugin>

Then /reload-plugins works because it fetches fresh on cache miss.

Expected behavior

/reload-plugins should invalidate the cache and re-fetch from the remote, or there should be a /reload-plugins --fresh flag that does this. Currently there's no built-in way to update plugins without knowing the cache path.

Steps to reproduce

1. Install a plugin from a personal marketplace: claude plugin install my-plugin@my-marketplace
2. Push changes to the marketplace repo (add a new skill, update a SKILL.md)
3. Run /reload-plugins
4. The new skill/changes are not visible
5. Manually rm -rf ~/.claude/plugins/cache/my-marketplace/my-plugin
6. Run /reload-plugins again
7. Now the changes appear

Environment

• macOS Darwin 24.6.0
• Plugin source: GitHub private repo marketplace