Add backend and db settings

server/routers/dogsitters-finder/json/2fa/error.json

@@ -0,0 +1,4 @@
+{
+  "status": "error",
+  "message": "Invalid code."
+}

server/routers/dogsitters-finder/json/2fa/success.json

@@ -0,0 +1,4 @@
+{
+  "status": "success",
+  "message": "Two-factor authentication passed."
+}