feat(frontend): add Dashboard page and components for #53

Implement the main dashboard homepage with:
- WelcomeHeader: Personalized greeting with user name
- DashboardQuickStats: Stats cards for projects, agents, issues, approvals
- RecentProjects: Dynamic grid showing 3-6 recent projects
- PendingApprovals: Action-required approvals section
- EmptyState: Onboarding experience for new users
- useDashboard hook: Mock data fetching with React Query

The dashboard serves as the authenticated homepage at /(authenticated)/
and provides quick access to all project management features.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/components/dashboard/EmptyState.tsx

@@ -0,0 +1,61 @@
+/**
+ * EmptyState Component
+ *
+ * Displays a welcome message for new users with no projects.
+ * Provides call-to-action to create first project.
+ *
+ * @see Issue #53
+ */
+
+'use client';
+
+import { Rocket, Bot, Settings } from 'lucide-react';
+import { Card, CardContent } from '@/components/ui/card';
+import { Button } from '@/components/ui/button';
+import { Link } from '@/lib/i18n/routing';
+
+export interface EmptyStateProps {
+  /** User's first name for personalization */
+  userName?: string;
+  /** Additional CSS classes */
+  className?: string;
+}
+
+export function EmptyState({ userName = 'there', className }: EmptyStateProps) {
+  return (
+    <Card className={className}>
+      <CardContent className="py-12 text-center">
+        <div className="mx-auto mb-6 flex h-16 w-16 items-center justify-center rounded-full bg-primary/10">
+          <Rocket className="h-8 w-8 text-primary" />
+        </div>
+
+        <h2 className="text-2xl font-bold">Welcome to Syndarix, {userName}!</h2>
+        <p className="mx-auto mt-2 max-w-md text-muted-foreground">
+          Get started by creating your first project. Our AI agents will help you
+          turn your ideas into reality.
+        </p>
+
+        <Button size="lg" asChild className="mt-6">
+          <Link href="/projects/new">Create Your First Project</Link>
+        </Button>
+
+        <div className="mt-8 flex flex-col items-center gap-4 sm:flex-row sm:justify-center">
+          <Link
+            href="/agents"
+            className="flex items-center gap-2 text-sm text-muted-foreground hover:text-primary"
+          >
+            <Bot className="h-4 w-4" />
+            Set up AI agent types
+          </Link>
+          <Link
+            href="/settings"
+            className="flex items-center gap-2 text-sm text-muted-foreground hover:text-primary"
+          >
+            <Settings className="h-4 w-4" />
+            Configure your account
+          </Link>
+        </div>
+      </CardContent>
+    </Card>
+  );
+}