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

src/frontend/api/mod.rs

@@ -22,6 +22,7 @@ pub mod roles;
 pub mod run_context;
 pub mod sessions;
 pub mod setup;
+pub mod shared_folders;
 pub mod transcribe_audio;
 pub mod transcribe_models;
 pub mod tts_models;
@@ -176,6 +177,12 @@ pub fn router() -> Router<Arc<Skald>> {
         .route("/users",                        get(users_mgmt::list).post(users_mgmt::create))
         .route("/users/{id}",                   put(users_mgmt::update).delete(users_mgmt::delete))
         .route("/users/{id}/password",          post(users_mgmt::reset_password))
+
+        // Shared on-disk folders (blueprint §6) — admin-curated, capability-gated.
+        .route("/shared-folders",               get(shared_folders::list).post(shared_folders::create))
+        .route("/shared-folders/{id}",          patch(shared_folders::update_description).delete(shared_folders::delete))
+        .route("/shared-folders/{id}/members",  post(shared_folders::add_member))
+        .route("/shared-folders/{id}/members/{user_id}", delete(shared_folders::remove_member))
         // Images (generated by image_generate tool)
         .route("/images/{task_id}",             get(images::get_image))
         // MCP tool-result media (images/audio/files returned by MCP servers)