feat: initial commit — backend API + student cabinet frontend

- Go backend: auth (JWT), points earn/spend, QR token generation,
  partners, admin grant/stats endpoints with chi router
- Next.js 14 frontend: login, student dashboard, transaction history,
  QR display, partners list
- PostgreSQL migrations (4 tables), Redis cache, Docker Compose
- CORS middleware, role-based route protection, Zustand auth store

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/lib/utils.ts

@@ -0,0 +1,32 @@
+// Utility helpers for formatting numbers and dates throughout the UI.
+
+/**
+ * Formats a point balance for display: 1234 → "1 234 pts"
+ * Uses the Russian locale so thousands are separated by a space.
+ */
+export function formatPoints(n: number): string {
+  return `${new Intl.NumberFormat('ru-RU').format(n)} pts`;
+}
+
+/**
+ * Formats a transaction amount with a sign prefix.
+ * Positive amounts use a "+" prefix; negative amounts use the Unicode minus sign "−".
+ * Example: 50 → "+50", -30 → "−30"
+ */
+export function formatTransactionAmount(amount: number): string {
+  if (amount >= 0) return `+${amount}`;
+  return `−${Math.abs(amount)}`; // U+2212 MINUS SIGN, visually distinct from hyphen
+}
+
+/**
+ * Formats a UTC ISO timestamp to a compact Russian date+time string.
+ * Example: "2024-04-28T14:32:00Z" → "28 апр., 14:32"
+ */
+export function formatDate(iso: string): string {
+  return new Intl.DateTimeFormat('ru-RU', {
+    day: 'numeric',
+    month: 'short',
+    hour: '2-digit',
+    minute: '2-digit',
+  }).format(new Date(iso));
+}