feat(plugins): plugin marketplace with discovery, settings, permissions, Wikipedia & OpenLibrary (M14.1-M14.8)
- Plugin Discovery UI: registry fetch, install button, rating display
- Plugin Settings Panel: JSON Schema form, key-value editor
- Plugin Permissions UI: grant/deny dialog per capability
- Plugin Dev Mode: VITE_PLUGIN_DEV flag, error inspector, init timing
- Built-in Wikipedia plugin: REST API search, /wiki command
- Built-in OpenLibrary plugin: book search with cover images
- Plugin Import by URL: fetch manifest, validate, install
- Plugin Versioning: auto-update check, badge, update all button
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
