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

web/css/models-llm.css

@@ -164,7 +164,7 @@
   padding: 0.15em 0.5em;
   border-radius: 4px;
   background: var(--bs-primary-bg-subtle, #eef2ff);
-  color: var(--bs-primary, #4f46e5);
+  color: var(--bs-primary, var(--accent-hover));
   flex-shrink: 0;
   white-space: nowrap;
 }
@@ -261,7 +261,7 @@
 }
 
 .llm-params-pill {
-  background: #6366f1 !important;
+  background: var(--accent) !important;
   color: #fff !important;
 }