feat(ws): send history data and update data with web socket

Added following logic:
1. New clients receive 15 entry history from history file
2. After that, every 10 seconds when new entry is generated it is sent
out to all connected clients

backend/consts.js

@@ -0,0 +1,6 @@
+// Define global constants for min and max values
+export const MAX = 100;
+export const MIN = 0;
+
+// Define range for random number generation
+export const RANGE = 0.3; // +-0.3 -> +-30% of previous number