Render README tables on the website

[yawkat]

The website renders README.md with mistune, which doesn't parse tables without the table plugin, so the "Choosing an API" table showed up as raw pipe text. This enables the plugin and adds basic table styling to markdown.css.

🤖 Generated with Claude Code

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.76%. Comparing base (4af910b) to head (b2cc511).
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Additional details and impacted files

@@            Coverage Diff            @@
##               main     #150   +/-   ##
=========================================
  Coverage     79.76%   79.76%           
  Complexity      562      562           
=========================================
  Files            42       42           
  Lines          1838     1838           
  Branches        247      247           
=========================================
  Hits           1466     1466           
  Misses          239      239           
  Partials        133      133           

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