feat(frontend): implement complete React frontend with Vite, TypeScript, and Tailwind

Complete frontend implementation (FE-001 to FE-006):

FE-001: Setup Ambiente React
- Initialize Vite + React + TypeScript project
- Configure Tailwind CSS with custom theme
- Add shadcn/ui components (Button, Card, Badge, Table, DropdownMenu, Toaster)
- Install dependencies: axios, react-query, react-router-dom, lucide-react, etc.
- Configure path aliases (@/components, @/lib, etc.)

FE-002: Configurazione API Client
- Create lib/api.ts with Axios instance
- Add TypeScript types for Scenario, Metrics, etc.
- Configure environment variable VITE_API_URL

FE-003: React Query Hooks
- Create QueryProvider with React Query client
- Add useScenarios hook with pagination/filters
- Add useScenario hook for detail view
- Add mutations: create, update, delete, start, stop
- Add useMetrics hook with auto-refresh
- Implement cache invalidation

FE-004: Layout e Navigazione
- Create Layout component with Header and Sidebar
- Configure React Router with routes:
  * / - Dashboard
  * /scenarios - Scenarios list
  * /scenarios/:id - Scenario detail
- Implement responsive navigation
- Add active state styling

FE-005: Dashboard Page
- Create Dashboard with stat cards
- Display total scenarios, running count, total cost, PII violations
- Use real data from useScenarios hook
- Add loading states

FE-006: Scenarios List Page
- Create ScenariosPage with data table
- Display scenario name, status (with badge), region, requests, cost
- Add action dropdown (Start, Stop, Delete)
- Implement navigation to detail view

Components Created:
- ui/button.tsx - Button component with variants
- ui/card.tsx - Card component with header/content/footer
- ui/badge.tsx - Badge component for status
- ui/table.tsx - Table component
- ui/dropdown-menu.tsx - Dropdown menu
- ui/toaster.tsx - Toast notifications

Pages Created:
- Dashboard.tsx - Main dashboard view
- ScenariosPage.tsx - List of scenarios
- ScenarioDetail.tsx - Scenario detail with metrics
- NotFound.tsx - 404 page

All features integrated with backend API.

Tasks: FE-001, FE-002, FE-003, FE-004, FE-005, FE-006 complete

frontend/src/components/ui/table.tsx

@@ -0,0 +1,116 @@
+import * as React from "react"
+import { cn } from "@/lib/utils"
+
+const Table = React.forwardRef<
+  HTMLTableElement,
+  React.HTMLAttributes<HTMLTableElement>
+>(({ className, ...props }, ref) => (
+  <div className="relative w-full overflow-auto">
+    <table
+      ref={ref}
+      className={cn("w-full caption-bottom text-sm", className)}
+      {...props}
+    />
+  </div>
+))
+Table.displayName = "Table"
+
+const TableHeader = React.forwardRef<
+  HTMLTableSectionElement,
+  React.HTMLAttributes<HTMLTableSectionElement>
+>(({ className, ...props }, ref) => (
+  <thead ref={ref} className={cn("[&_tr]:border-b", className)} {...props} />
+))
+TableHeader.displayName = "TableHeader"
+
+const TableBody = React.forwardRef<
+  HTMLTableSectionElement,
+  React.HTMLAttributes<HTMLTableSectionElement>
+>(({ className, ...props }, ref) => (
+  <tbody
+    ref={ref}
+    className={cn("[&_tr:last-child]:border-0", className)}
+    {...props}
+  />
+))
+TableBody.displayName = "TableBody"
+
+const TableFooter = React.forwardRef<
+  HTMLTableSectionElement,
+  React.HTMLAttributes<HTMLTableSectionElement>
+>(({ className, ...props }, ref) => (
+  <tfoot
+    ref={ref}
+    className={cn(
+      "border-t bg-muted/50 font-medium [&>tr]:last:border-b-0",
+      className
+    )}
+    {...props}
+  />
+))
+TableFooter.displayName = "TableFooter"
+
+const TableRow = React.forwardRef<
+  HTMLTableRowElement,
+  React.HTMLAttributes<HTMLTableRowElement>
+>(({ className, ...props }, ref) => (
+  <tr
+    ref={ref}
+    className={cn(
+      "border-b transition-colors hover:bg-muted/50 data-[state=selected]:bg-muted",
+      className
+    )}
+    {...props}
+  />
+))
+TableRow.displayName = "TableRow"
+
+const TableHead = React.forwardRef<
+  HTMLTableCellElement,
+  React.ThHTMLAttributes<HTMLTableCellElement>
+>(({ className, ...props }, ref) => (
+  <th
+    ref={ref}
+    className={cn(
+      "h-12 px-4 text-left align-middle font-medium text-muted-foreground [&:has([role=checkbox])]:pr-0",
+      className
+    )}
+    {...props}
+  />
+))
+TableHead.displayName = "TableHead"
+
+const TableCell = React.forwardRef<
+  HTMLTableCellElement,
+  React.TdHTMLAttributes<HTMLTableCellElement>
+>(({ className, ...props }, ref) => (
+  <td
+    ref={ref}
+    className={cn("p-4 align-middle [&:has([role=checkbox])]:pr-0", className)}
+    {...props}
+  />
+))
+TableCell.displayName = "TableCell"
+
+const TableCaption = React.forwardRef<
+  HTMLTableCaptionElement,
+  React.HTMLAttributes<HTMLTableCaptionElement>
+>(({ className, ...props }, ref) => (
+  <caption
+    ref={ref}
+    className={cn("mt-4 text-sm text-muted-foreground", className)}
+    {...props}
+  />
+))
+TableCaption.displayName = "TableCaption"
+
+export {
+  Table,
+  TableHeader,
+  TableBody,
+  TableFooter,
+  TableHead,
+  TableRow,
+  TableCell,
+  TableCaption,
+}