docs: revamp content and improve documentation UI

[mckaragoz]

Summary

Revamps the documentation to provide a clearer introduction to UltimateAuth's architecture, authentication models, client profiles, and request lifecycle.

Also improves the documentation UI for better readability and developer experience.

Changes

• Revised and reorganized old section's documentation content.
• Improved documentation typography, spacing, links, and table styling.
• Added responsive table wrappers.
• Enhanced code blocks with language headers, syntax highlighting, and copy buttons.
• Improved static asset caching with fingerprinted CSS and JavaScript references.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.98%. Comparing base (28ef1e7) to head (66ef14a).

Additional details and impacted files

@@            Coverage Diff             @@
##              dev      #82      +/-   ##
==========================================
- Coverage   85.98%   85.98%   -0.01%     
==========================================
  Files         660      660              
  Lines       18275    18275              
  Branches     2249     2249              
==========================================
- Hits        15714    15713       -1     
- Misses       1810     1811       +1     
  Partials      751      751              

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