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.
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.
