Serve static graphical frontend with PicoCSS and Chart.js based on the web API

[memowe]

based on #10 but fix #9 first

Tabs/options

• This week
• Last week
• This month
• Last month
• This year
• Last year
• Overall

Not the same visualizations on all tabs.

Ideas

• GitHub-like grid with heatmap-like colours (maybe at the top on all the pages
• Week/month focus: rows of bars that expand to multiple bars for each day on click
• Tool tips with details for the day/the current block
• Tag cloud for a given time frame
• Tag pie chart for a given time frame
• Histogram for a given category or tag over large time frames (years/overall)
• Reproducible color coding for categories or tags?

Technology

KISS!

• all loaded from one static file (t4-api/static/report.html) via CDNs
• Pico CSS - responsive pretty styling
• Chart.js - most visualizations
• Some vanilla JS