Simplify overview page

[patrikbraborec]

Summary

• Remove content from the overview page that duplicates the quick start guide (authentication, running Actors, providing input, getting results)
• Streamline prerequisites and installation sections
• Keep a single quick example with async/sync tabs
• Align the overview structure with the JS client overview style

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.60%. Comparing base (a293601) to head (cc84ce5).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #646      +/-   ##
==========================================
- Coverage   96.62%   96.60%   -0.03%     
==========================================
  Files          45       45              
  Lines        4271     4271              
==========================================
- Hits         4127     4126       -1     
- Misses        144      145       +1     

Flag	Coverage Δ
integration	94.59% <ø> (-0.05%)	⬇️
unit	75.60% <ø> (ø)

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