feat(ui): refactor components and enhance UX

Updated various UI components to improve user experience and maintainability. Key changes include:
- Refactored `PageHeader` to remove icon handling, simplifying its structure.
- Replaced `KpiMetricsGrid` with `SectionCards` for better layout consistency.
- Enhanced `AppShell` and navigation components to utilize a grouped navigation structure, improving accessibility and organization.
- Introduced new properties in `crud-list-page` for handling empty states and loading indicators.
- Updated styles and classes for better visual consistency across components.

These changes streamline the UI and enhance the overall user experience across the application.

.cursor/rules/frontend-ui-patterns.mdc

@@ -31,7 +31,7 @@ apps/web/src/lib/components/  ← shared + domain + layout
 | Элемент | Компонент | Primitive |
 |---------|-----------|-----------|
 | Page wrapper | `PageShell` | — |
-| Page title | `PageHeader` (`ui/app/page-header`) | — |
+| Page title | `PageHeader` (`ui/app/page-header`) — **без icon** | — |
 | Stat metrics | `SectionCards` | `Card` |
 | Data list | `DataTableCard` + `AppDataTable` | `Table` |
 | Filters | `ListFiltersBar` | `Select`, `Badge` |
@@ -40,8 +40,16 @@ apps/web/src/lib/components/  ← shared + domain + layout
 | Status | `StatusBadge` | `Badge` |
 | Create/Edit form | `FormSheet` / Dialog | `Sheet`, `Field` |
 | Delete confirm | `ConfirmDialog` | `AlertDialog` |
-| Nav | `AppShell` | `Sidebar` |
-| Breadcrumbs | `AppShell` header | `Breadcrumb` |
+| Nav | `AppShell` + `navGroups` | `Sidebar` |
+| Breadcrumbs | `AppShell` header (parent route) | `Breadcrumb` |
+| Tabs (dashboard, ops) | `LINE_TAB_TRIGGER_CLASS` | `Tabs` |
+
+## Запрещено
+
+- `icon` / `iconClass` в `PageHeader`
+- `KpiMetricsGrid` — только `SectionCards`
+- `mx-auto max-w-*` на `PageShell` list-страниц
+- Голый `AppDataTable` без `DataTableCard` на list-экранах
 
 ## Spacing