Introduce the x-icon custom element and migrate first-party WebUI and bundled plugin markup while retaining legacy Material icon compatibility. Defer icon-font readiness until the splash-installed document is parsed so Firefox does not leave icons transparent. Centralize chat message collapse handling, avoid false Show More controls on short user messages, and align grouped-message pagination styling. Update DOX and add regression coverage for the icon and collapse behavior.
Add a new per-plugin actions dropdown to the plugin list and expose new HTML extension points inside it so plugins can inject custom dropdown entries while empty menus stay hidden.
Also add a fire-and-forget JS hook after `plugins_list` loads, with `_plugin_installer` owning the cached marketplace index fetch and deep-link helper so matching installed plugins get a Marketplace action that opens the exact marketplace detail.
Change all plugin modal path references from relative (`../plugins/`) to absolute (`/plugins/`) URLs for consistency and to avoid path resolution issues across different webui components.
