Feature Request: Persistent --plugin-dir for local plugin development

The --plugin-dir flag lets you load a plugin directly from a local directory without the cache, which is exactly what plugin developers need. But it's session-only — you have to pass it on every launch. For developers actively iterating on a plugin locally, this means either re-specifying the flag every time or hacking installed_plugins.json to work around the marketplace/cache system. Could --plugin-dir paths be persisted in settings (e.g., claude config add plugin_dirs ~/projects/my-plugin) so they survive across sessions? This would give plugin developers a first-class workflow without needing any changes to the marketplace or caching architecture.