feat: add dashboard, projects, and persons pages with reusable components

Implemented the following:
- `DashboardPage`: displays an overview of stats, recent projects, and tabs for future analytics/reports.
- `ProjectsPage` and `PersonsPage`: include searchable tables, actions, and mobile-friendly card views.
- Integrated reusable components like `AuthLoading`, `DropdownMenu`, `Table`, and `Card`.

frontend/app/auth/callback/page.tsx

@@ -0,0 +1,79 @@
+"use client";
+
+import { useEffect, useState } from "react";
+import { useRouter } from "next/navigation";
+import { Loader2 } from "lucide-react";
+import { useAuth } from "@/lib/auth-context";
+
+export default function CallbackPage() {
+  const router = useRouter();
+  const [error, setError] = useState<string | null>(null);
+  const { login, user } = useAuth();
+
+  useEffect(() => {
+    async function handleCallback() {
+      try {
+        // Get the code from the URL query parameters
+        const urlParams = new URLSearchParams(window.location.search);
+        const code = urlParams.get('code');
+
+        if (!code) {
+          throw new Error('No authorization code found in the URL');
+        }
+
+        // Use the auth context to login
+        await login(code);
+
+        // Check if there's a stored callbackUrl
+        const callbackUrl = sessionStorage.getItem('callbackUrl');
+
+        // Clear the stored callbackUrl
+        sessionStorage.removeItem('callbackUrl');
+
+        // Redirect based on role and callbackUrl
+        if (callbackUrl) {
+          // For admin routes, check if user has admin role
+          if (callbackUrl.startsWith('/admin') && user?.role !== 'ADMIN') {
+            router.push('/dashboard');
+          } else {
+            router.push(callbackUrl);
+          }
+        } else {
+          // Default redirects if no callbackUrl
+          if (user && user.role === 'ADMIN') {
+            router.push('/admin');
+          } else {
+            router.push('/dashboard');
+          }
+        }
+      } catch (err) {
+        console.error("Authentication error:", err);
+        setError("Une erreur est survenue lors de l'authentification. Veuillez réessayer.");
+      }
+    }
+
+    handleCallback();
+  }, [router]);
+
+  if (error) {
+    return (
+      <div className="flex min-h-screen flex-col items-center justify-center p-4 text-center">
+        <div className="mb-4 text-red-500">{error}</div>
+        <a
+          href="/auth/login"
+          className="text-primary hover:underline"
+        >
+          Retour à la page de connexion
+        </a>
+      </div>
+    );
+  }
+
+  return (
+    <div className="flex min-h-screen flex-col items-center justify-center p-4 text-center">
+      <Loader2 className="mb-4 h-8 w-8 animate-spin text-primary" />
+      <h1 className="mb-2 text-xl font-semibold">Authentification en cours...</h1>
+      <p className="text-muted-foreground">Vous allez être redirigé vers l'application.</p>
+    </div>
+  );
+}