Introduces a persistent plugins.json config to track enabled/disabled status for plugins, updates the plugin manager to respect this config when loading plugins, and adds API and frontend support for toggling plugin status. The backend now reports plugin status as 'active', 'stopped', or 'disabled', and the frontend displays these states with appropriate labels. Also updates the built-in plugin package.json with author info.
Implemented backend API and router for plugin management (list, reload, enable/disable, uninstall) and exposed corresponding frontend controller and dashboard page. Updated navigation and site config to include plugin management. Refactored plugin manager adapter for public methods and improved plugin metadata handling.
