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>

migrations/00001_init_users.sql

@@ -0,0 +1,19 @@
+-- +goose Up
+CREATE TABLE users (
+    id          UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    email       TEXT NOT NULL UNIQUE,
+    name        TEXT NOT NULL,
+    -- student_id is NULL for partner and admin accounts
+    student_id  TEXT UNIQUE,
+    password_hash TEXT NOT NULL,
+    role        TEXT NOT NULL CHECK (role IN ('student', 'partner', 'admin')),
+    -- balance is denormalised for read performance; always updated atomically with transactions table
+    balance     INTEGER NOT NULL DEFAULT 0 CHECK (balance >= 0),
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX ON users(email);
+CREATE INDEX ON users(role);
+
+-- +goose Down
+DROP TABLE IF EXISTS users;