Plot timestamp displays in UTC instead of timezone defined in .env

[mmatuszewsky]

It sometimes happens that when plotting some data the timestamp on the x-axis is displayed as UTC timezone.

Timestamp is created inside node_handler.py file
Files probably affected: components/plots/Plot.svelte

Proper flow should be:

1. (backend) node_handler creates utc timestamp
2. (frontend) based on the value inside vite.config.js it should convert timestamp to given timezone.