docs: Improve content script UI docs

[aklinker1]

This PR aims to improve readability of content script UI docs, as mentioned in #267.

• Moved from /entrypoints/content-scripts.html to /guide/content-script-ui.html
• Added visualizations for several options
• Added a whole new section for "integrated" UIs
• Better examples for all frameworks
• Export more types so they show up in the API reference

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[codecov]

Codecov Report

Attention: 9 lines in your changes are missing coverage. Please review.

Comparison is base (2ef28ec) 69.99% compared to head (0e2ddfb) 69.97%.

Files	Patch %	Lines
src/client/index.ts	0.00%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #268      +/-   ##
==========================================
- Coverage   69.99%   69.97%   -0.02%     
==========================================
  Files         133      133              
  Lines        7338     7365      +27     
  Branches      571      571              
==========================================
+ Hits         5136     5154      +18     
- Misses       2152     2161       +9     
  Partials       50       50              

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