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/pages/ScenarioDetail.tsx

@@ -0,0 +1,77 @@
+import { useParams } from 'react-router-dom';
+import { useScenario } from '@/hooks/useScenarios';
+import { useMetrics } from '@/hooks/useMetrics';
+import { Badge } from '@/components/ui/badge';
+import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
+
+const statusColors = {
+  draft: 'secondary',
+  running: 'default',
+  completed: 'outline',
+  archived: 'destructive',
+} as const;
+
+export function ScenarioDetail() {
+  const { id } = useParams<{ id: string }>();
+  const { data: scenario, isLoading: isLoadingScenario } = useScenario(id || '');
+  const { data: metrics, isLoading: isLoadingMetrics } = useMetrics(id || '');
+
+  if (isLoadingScenario || isLoadingMetrics) {
+    return <div>Loading...</div>;
+  }
+
+  if (!scenario) {
+    return <div>Scenario not found</div>;
+  }
+
+  return (
+    <div className="space-y-6">
+      <div className="flex justify-between items-start">
+        <div>
+          <h1 className="text-3xl font-bold">{scenario.name}</h1>
+          <p className="text-muted-foreground">{scenario.description}</p>
+        </div>
+        <Badge variant={statusColors[scenario.status]}>
+          {scenario.status}
+        </Badge>
+      </div>
+
+      <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-4">
+        <Card>
+          <CardHeader className="pb-2">
+            <CardTitle className="text-sm font-medium">Total Requests</CardTitle>
+          </CardHeader>
+          <CardContent>
+            <div className="text-2xl font-bold">{metrics?.summary.total_requests || 0}</div>
+          </CardContent>
+        </Card>
+        <Card>
+          <CardHeader className="pb-2">
+            <CardTitle className="text-sm font-medium">Total Cost</CardTitle>
+          </CardHeader>
+          <CardContent>
+            <div className="text-2xl font-bold">
+              ${(metrics?.summary.total_cost_usd || 0).toFixed(6)}
+            </div>
+          </CardContent>
+        </Card>
+        <Card>
+          <CardHeader className="pb-2">
+            <CardTitle className="text-sm font-medium">SQS Blocks</CardTitle>
+          </CardHeader>
+          <CardContent>
+            <div className="text-2xl font-bold">{metrics?.summary.sqs_blocks || 0}</div>
+          </CardContent>
+        </Card>
+        <Card>
+          <CardHeader className="pb-2">
+            <CardTitle className="text-sm font-medium">LLM Tokens</CardTitle>
+          </CardHeader>
+          <CardContent>
+            <div className="text-2xl font-bold">{metrics?.summary.llm_tokens || 0}</div>
+          </CardContent>
+        </Card>
+      </div>
+    </div>
+  );
+}