feat: implementasi Kodeva - sistem manajemen kursus coding

Fitur lengkap:
- Auth JWT + RBAC (Admin/Teacher) + halaman login
- Shell 3 kolom (left nav, topbar, right rail dashboard)
- CRUD siswa + follow up kanban + status calon/student/ex
- Dashboard: siswa aktif, kehadiran, bar sumber lead, perlu follow up
- Pembayaran prorata per pertemuan (cash/transfer/qris)
- Kelas, enrollment, generate sesi, kehadiran bulk
- Jurnal aktivitas + upload multi-foto
- Raport + placement test (tampil di detail siswa)
- Pengaturan & seed data contoh

Stack: Next.js 16, TypeScript, Tailwind v4, Prisma (SQLite), Recharts, Zod

src/components/ui/stat-card.tsx

@@ -0,0 +1,39 @@
+import type { ReactNode } from "react";
+import Link from "next/link";
+import { cn } from "@/lib/utils";
+
+export function StatCard({
+  label,
+  value,
+  icon,
+  gradient = "grad-primary",
+  delta,
+  hint,
+  href,
+}: {
+  label: string;
+  value: ReactNode;
+  icon: ReactNode;
+  gradient?: string;
+  delta?: string;
+  hint?: string;
+  href?: string;
+}) {
+  const body = (
+    <div className="flex h-full items-center gap-4 rounded-[20px] border border-ink-100 bg-surface p-4 shadow-[var(--shadow-sm)] transition-all duration-150 hover:-translate-y-0.5 hover:shadow-[var(--shadow-md)]">
+      <span className={cn("flex size-11 shrink-0 items-center justify-center rounded-[14px] text-white", gradient)}>
+        {icon}
+      </span>
+      <div className="min-w-0">
+        <p className="truncate text-[12px] font-medium text-ink-500">{label}</p>
+        <div className="flex items-baseline gap-2">
+          <p className="font-num text-[26px] font-bold leading-tight text-ink-900">{value}</p>
+          {delta ? <span className="text-[12px] font-semibold text-mint-500">{delta}</span> : null}
+        </div>
+        {hint ? <p className="truncate text-[11px] text-ink-500">{hint}</p> : null}
+      </div>
+    </div>
+  );
+  if (href) return <Link href={href}>{body}</Link>;
+  return body;
+}