docs: Add Scrapling guide

[vdusek]

Adds a new guide for using the Scrapling adaptive web scraping library in Apify Actors, following the structure of the existing scraping-library guides (BeautifulSoup, Playwright, Scrapy).

What's included

• docs/03_guides/09_scrapling.mdx — the guide: introduction & features, choosing a fetcher (HTTP vs. browser-based), a runnable example Actor, Apify Proxy integration, and a section on running browser-based fetchers (DynamicFetcher/StealthyFetcher) with the required scrapling install step in the Dockerfile.
• docs/03_guides/code/09_scrapling.py — the runnable example: a recursive title scraper using Scrapling's async HTTP AsyncFetcher through Apify Proxy.
• Link to the new guide added to the quick-start "Guides" list.

Verification

• The example Actor was run locally (apify run) and on the Apify platform (build + run SUCCEEDED), producing correct dataset output with Apify Proxy.
• The browser-based path from the guide (Apify Playwright base image + scrapling install) was also built and run on the platform to confirm the Dockerfile works — DynamicFetcher extracted data through a real browser.
• ruff check docs/ and ty check pass.

Numbered 09 to sit after the in-progress uv guide (#932), which takes 08.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.98%. Comparing base (24a6edb) to head (2a41a3f).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #938      +/-   ##
==========================================
+ Coverage   86.94%   86.98%   +0.03%     
==========================================
  Files          48       48              
  Lines        2942     2942              
==========================================
+ Hits         2558     2559       +1     
+ Misses        384      383       -1     

Flag	Coverage Δ
e2e	37.76% <ø> (+0.20%)	⬆️
integration	59.14% <ø> (+0.23%)	⬆️
unit	75.69% <ø> (ø)

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