Major rebranding, i18n, dashboard, shared folders, role capabilities

- Rebrand: new app/agent icons, SKALD.md, warm "paper" CSS palette
  (terracotta accent, --radius tokens, WCAG contrast, reduced-motion),
  updated favicon, tray icon, skaldkonur asset
- i18n: backend crate (i18n.rs, locale column, ui_locale config),
  frontend library (web/lib/i18n.js, I18nMixin, t(key)),
  translation files (web/i18n/), every component wired
- Dashboard: <dashboard-page> replaces old home-page content;
  <app-copilot> becomes the landing page (full/dock layout modes)
- Shared folders: API endpoints (shared_folders.rs), frontend page,
  can_write membership, container mount topology, user_fs routing
- Role capabilities: new db table & authorization seam (data not enums),
  roles.attrs JSON for ui_mode / interface select
- Setup: skald-setup prompts for language + password, sets ui_locale
- General: components migrated to CSS variables, Lit conventions cleanup,
  connectors/catalog/marketplace/approval refactoring

crates/skald-core/src/skald/bundles.rs

@@ -346,7 +346,7 @@ impl Conversation {
 
         // The ownerless manager is inert (no loops, no consumers — see §19): it takes
         // a placeholder UserFs purely to satisfy the type, never used to resolve a path.
-        let ownerless_fs = Arc::new(core_api::user_fs::UserFs::new(
+        let ownerless_fs = core_api::user_fs::SharedFs::new(core_api::user_fs::UserFs::new(
             String::new(),
             std::path::PathBuf::from("homes"),
             "skald-ownerless",