Device Detail: Click-to-label activity on live chart

[crazyideas21]

Enable user to click-drag over time ranges in live traffic chart and assign labels; store label + timestamp for downstream ML evaluation.

[AndrewQuijano]

@crazyideas21 I assume this will also be a task once I get the GUI working? Just want to avoid cutting duplicate issues

[crazyideas21]

Too complex for the user; instead, we're doing #239