add basic functionality for frontend, json db

data/preregistered.json

@@ -0,0 +1,15 @@
+{
+  "rawData": {
+    "424297319": {
+      "name": "Зимин Владислав",
+      "availableTime": {
+        "from": 30,
+        "to": 40
+      },
+      "tgUsername": "swq_2018",
+      "chatId": 424297319,
+      "userId": "424297319"
+    }
+  },
+  "groups": []
+}