docs: Add more badges to the README

[samestep]

This PR adds the following badges to README.md:

• code coverage (currently 69%)
• code style (Prettier)
• license (MIT)
• Twitter

[cloudflare-pages]

Deploying with    Cloudflare Pages

Latest commit:	6e26c09
Status:	✅  Deploy successful!
Preview URL:	https://41cb3850.penrose-panes.pages.dev

View logs

[codecov]

Codecov Report

Merging #838 (9c8d1ac) into main (7d5538b) will not change coverage.
The diff coverage is n/a.

❗ Current head 9c8d1ac differs from pull request most recent head 6e26c09. Consider uploading reports for the commit 6e26c09 to get more accurate results

@@           Coverage Diff           @@
##             main     #838   +/-   ##
=======================================
  Coverage   68.85%   68.85%           
=======================================
  Files          61       61           
  Lines        7725     7725           
  Branches     1454     1454           
=======================================
  Hits         5319     5319           
  Misses       2393     2393           
  Partials       13       13           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7d5538b...6e26c09. Read the comment docs.