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>

backend/cmd/seed/main.go

@@ -0,0 +1,84 @@
+// seed inserts development test users into the database.
+// Run via: make seed  (only use against local dev DB, never production)
+package main
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+	"golang.org/x/crypto/bcrypt"
+)
+
+type seedUser struct {
+	email     string
+	name      string
+	password  string
+	role      string
+	studentID string // empty string → NULL in DB
+}
+
+var devUsers = []seedUser{
+	{
+		email:     "student@cu.ru",
+		name:      "Иван Студентов",
+		password:  "password123",
+		role:      "student",
+		studentID: "STU001",
+	},
+	{
+		email:    "partner@cu.ru",
+		name:     "Кофейня Уют",
+		password: "password123",
+		role:     "partner",
+	},
+	{
+		email:    "admin@cu.ru",
+		name:     "Администратор ЦУ",
+		password: "password123",
+		role:     "admin",
+	},
+}
+
+func main() {
+	dbURL := os.Getenv("DATABASE_URL")
+	if dbURL == "" {
+		slog.Error("DATABASE_URL is not set")
+		os.Exit(1)
+	}
+
+	ctx := context.Background()
+	db, err := pgxpool.New(ctx, dbURL)
+	if err != nil {
+		slog.Error("connect failed", "err", err)
+		os.Exit(1)
+	}
+	defer db.Close()
+
+	for _, u := range devUsers {
+		hash, err := bcrypt.GenerateFromPassword([]byte(u.password), bcrypt.DefaultCost)
+		if err != nil {
+			slog.Error("bcrypt failed", "email", u.email, "err", err)
+			os.Exit(1)
+		}
+
+		// NULLIF converts empty string to NULL for student_id
+		_, err = db.Exec(ctx, `
+			INSERT INTO users (email, name, password_hash, role, student_id)
+			VALUES ($1, $2, $3, $4, NULLIF($5, ''))
+			ON CONFLICT (email) DO UPDATE
+				SET password_hash = EXCLUDED.password_hash,
+				    name          = EXCLUDED.name
+		`, u.email, u.name, string(hash), u.role, u.studentID)
+		if err != nil {
+			slog.Error("seed insert failed", "email", u.email, "err", err)
+			os.Exit(1)
+		}
+
+		fmt.Printf("seeded: %-30s  role=%-8s  password=%s\n", u.email, u.role, u.password)
+	}
+
+	fmt.Println("\nDone. Test credentials above are for local development only.")
+}