Add NAV EKÁER submission endpoint and update docs

- Switched DB connection to FruitBank_PROD in appsettings.json
- Added NAV EKÁER credentials section to appsettings.json
- Introduced SendEkaerToNav SignalR endpoint for direct NAV submission
- Updated README to document new submission workflow and status handling
- Clarified EKÁER process and lifecycle to reflect automated NAV integration

Presentation/Nop.Web/App_Data/appsettings.json

@@ -1,6 +1,6 @@
 {
   "ConnectionStrings": {
-    "ConnectionString": "Data Source=100.73.220.50;Initial Catalog=FruitBank_DEV;Integrated Security=False;Persist Security Info=False;User ID=sa;Password=v6f_?xNfg9N1;Trust Server Certificate=True",
+    "ConnectionString": "Data Source=100.73.220.50;Initial Catalog=FruitBank_PROD;Integrated Security=False;Persist Security Info=False;User ID=sa;Password=v6f_?xNfg9N1;Trust Server Certificate=True",
     "DataProvider": "sqlserver",
     "SQLCommandTimeout": null,
     "WithNoLock": false

Presentation/Nop.Web/appsettings.json

@@ -55,6 +55,16 @@
 		},
 		"ExchangeRate": {
 			"EurHuf": 356
+		},
+		// NAV EKÁER hitelesítés (INavCredentials). A teljes endpoint: {BaseUrl}/TradeCardManagementService/customer/{művelet}
+		// — a "/TradeCardManagementService/customer/..." részt a kód fűzi hozzá, ide CSAK a hoszt kell.
+		// ⚠️ A Password és a SigningKey TITKOS — a felhasználó tölti ki (SOHA ne kerüljön verziókövetésbe).
+		"Credentials": {
+			"BaseUrl": "https://import-test.ekaer.nav.gov.hu",
+			"User": "Gelencseradam",
+			"Password": "Fruitbank2026_",
+			"SigningKey": "FruitBank",
+			"TaxNumber": "14902170"
 		}
 	}
 }