docs: fix AI agents guide examples and raise the runnable-example timeout

[vdusek]

Follow-up fixes to the AI agents guide (#995) after testing the five framework examples on the platform.

CrewAI

The researcher agent answered from the model's own knowledge instead of scraping the page, so it returned JavaScript Crawlee crawlers (CheerioCrawler, PuppeteerCrawler, ...) that don't exist in Python Crawlee. Its goal / backstory and the research task now require the web_browser tool and answering only from the fetched Markdown, so the output is grounded in the actual Python Crawlee docs page.

LlamaIndex

It's the heaviest example. It downloads a local HuggingFace embedding model and uses the browser-based Website Content Crawler, so a cold start exceeded the 180 s the docs "Run" button allotted and got aborted mid-index. Raised the docs "Run" button timeout to 360 s for all runnable examples (website/roa-loader).

Both docs/ and the website/versioned_docs/version-3.4/ mirror are updated identically.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.78%. Comparing base (e11fa8d) to head (382e8c4).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1035      +/-   ##
==========================================
+ Coverage   91.75%   91.78%   +0.03%     
==========================================
  Files          50       50              
  Lines        3215     3215              
==========================================
+ Hits         2950     2951       +1     
+ Misses        265      264       -1     

Flag	Coverage Δ
e2e	35.64% <ø> (ø)
integration	57.41% <ø> (+0.03%)	⬆️
unit	83.07% <ø> (ø)

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