add charts to display some time series data

Add a chart display to show time series data such as ventilator parameters

e.g. we can use chart.js

This depends on #9 being completed, so that we have a source of time series data.
It also depends on #14 being completed so that there is a suitable place to display the chart.

First review issues #9 and #14 to understand the time-series data source and the intended display location. Then identify the relevant frontend entry points and determine how a chart.js display should present ventilator parameters; done means the chart renders the available time-series data in that location.

Written by the indexing model from the issue text.