feat(api): .NET 10 multi-tenant REST API

Full backend implementation:
- Multi-tenant cafe/restaurant management (menus, orders, tables, staff)
- POS order flow with ZarinPal and Snappfood payment integration
- OTP authentication via Kavenegar SMS
- QR digital menu with public discover/finder endpoints
- Customer loyalty, coupons, CRM
- PostgreSQL via EF Core, Redis for caching/sessions
- Background jobs, webhook handlers
- Full migration history

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

data/demo-credentials.json

@@ -0,0 +1,34 @@
+{
+  "version": 1,
+  "environment": "development",
+  "cafe": {
+    "id": "cafe_demo_001",
+    "slug": "demo-cafe",
+    "name": "کافه دمو"
+  },
+  "branch": {
+    "id": "branch_demo_main",
+    "name": "شعبه اصلی"
+  },
+  "auth": {
+    "note": "در محیط Development با OTP توسعه وارد شوید (کد در لاگ API).",
+    "otpDevBypass": true
+  },
+  "systemAdmin": {
+    "phone": "09120000001",
+    "note": "ورود مدیر سامانه: /fa/admin/login — OTP در لاگ API"
+  },
+  "employees": [
+    { "id": "emp_demo_owner", "name": "مدیر دمو", "phone": "09121234567", "role": "Owner" },
+    { "id": "emp_demo_manager", "name": "مدیر شعبه", "phone": "09121111111", "role": "Manager" },
+    { "id": "emp_demo_cashier", "name": "صندوقدار", "phone": "09122222222", "role": "Cashier" },
+    { "id": "emp_demo_waiter", "name": "گارسون", "phone": "09123333333", "role": "Waiter" },
+    { "id": "emp_demo_waiter2", "name": "گارسون ۲", "phone": "09124444444", "role": "Waiter" },
+    { "id": "emp_demo_chef", "name": "آشپز", "phone": "09125555555", "role": "Chef" },
+    { "id": "emp_demo_delivery", "name": "پیک", "phone": "09126666666", "role": "Delivery" }
+  ],
+  "publicQr": {
+    "tableQr": "demo_table_01",
+    "discoverSlug": "demo-cafe"
+  }
+}