Refactor app architecture and clean local artifacts

Backend/appsettings.json

@@ -1,6 +1,20 @@
 {
+  "Frontend": {
+    "AllowedOrigins": []
+  },
   "ConnectionStrings": {
-    "Postgres": "Host=localhost;Port=5432;Database=vtuber_star_awards;Username=postgres;Password=postgres"
+    "Postgres": ""
+  },
+  "SeedData": {
+    "Mode": "none"
+  },
+  "DemoAdmin": {
+    "Enabled": false,
+    "Login": "",
+    "Email": "",
+    "Password": "",
+    "TwitchUserId": "jayuhime_admin",
+    "DisplayName": "Jayuhime Admin"
   },
   "Logging": {
     "LogLevel": {