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/sidebar.css

@@ -17,8 +17,8 @@ app-sidebar {
   gap: 0.55rem;
   padding: 0 1rem 1.25rem;
   color: var(--sidebar-brand-color);
-  font-size: 0.95rem;
-  font-weight: 600;
+  font-size: 1.05rem;
+  font-weight: 700;
   letter-spacing: 0.01em;
 }
 
@@ -89,11 +89,11 @@ app-sidebar {
   display: flex;
   align-items: center;
   gap: 0.6rem;
-  padding: 0.20rem 0.30rem;
+  padding: 0.4rem 0.55rem;
   color: var(--sidebar-text);
   text-decoration: none;
-  font-size: 0.875rem;
-  border-radius: 0.25rem;
+  font-size: 0.92rem;
+  border-radius: 0.5rem;
   transition: background 0.12s, color 0.12s;
 }
 
@@ -119,8 +119,8 @@ app-sidebar {
 .sidebar-link.active {
   background: var(--sidebar-active-bg);
   color: var(--sidebar-text-active);
-  font-weight: 500;
-  border-radius: 0.25rem;
+  font-weight: 600;
+  border-radius: 0.5rem;
 }
 
 .sidebar-link.active i {
@@ -183,11 +183,11 @@ app-sidebar {
   display: flex;
   align-items: center;
   gap: 0.55rem;
-  padding: 0.18rem 0.40rem;
+  padding: 0.32rem 0.55rem;
   color: var(--sidebar-text);
   text-decoration: none;
-  font-size: 0.84rem;
-  border-radius: 0.25rem;
+  font-size: 0.86rem;
+  border-radius: 0.5rem;
   transition: background 0.12s, color 0.12s;
 }