feat: add authentication and user management features

- Implemented AuthButton component for Discord sign-in and sign-out functionality.
- Created CopyButton component for copying server IP addresses.
- Developed EventCard and GradeCard components for displaying events and grades.
- Added Footer and Navbar components for site navigation and information.
- Introduced PurchaseButton for handling grade purchases with Stripe integration.
- Created SectionHeader component for consistent section titles.
- Implemented session management with SessionProvider for NextAuth.
- Set up PostgreSQL database with Docker and Prisma for data management.
- Added admin guard functionality to restrict access to certain routes.
- Configured NextAuth with Discord provider for user authentication.
- Defined Prisma schema for user, admin, grade, event, and purchase models.
- Seeded database with initial grades and events data.
- Added SVG hero image for the landing page.
- Extended NextAuth types to include additional user properties.

types/next-auth.d.ts

@@ -0,0 +1,25 @@
+import "next-auth";
+
+declare module "next-auth" {
+  interface Session {
+    user: {
+      id: string;
+      name?: string | null;
+      email?: string | null;
+      image?: string | null;
+      discordId?: string;
+      discordUsername?: string;
+      discordAvatar?: string;
+      isAdmin?: boolean;
+    };
+  }
+}
+
+declare module "next-auth/jwt" {
+  interface JWT {
+    discordId?: string;
+    discordUsername?: string;
+    discordAvatar?: string;
+    isAdmin?: boolean;
+  }
+}