fix: respect scan_full_page=False for viewport-only screenshots

[Br1an67]

Summary

Fixes #1750

When scan_full_page=False, take_screenshot() still produced a full-page stitched screenshot because page_need_scroll() always triggered take_screenshot_scroller for pages taller than the viewport. Now, when scan_full_page=False, take_screenshot() directly calls take_screenshot_naive() which captures only the viewport area at the configured resolution.

List of files changed and why

crawl4ai/async_crawler_strategy.py — Pass scan_full_page from config to take_screenshot(); skip scroll-based stitching when scan_full_page=False and return viewport-only screenshot.

How Has This Been Tested?

Verified the logic flow: with scan_full_page=False, take_screenshot() now returns early with take_screenshot_naive() which uses page.screenshot(full_page=False) — capturing exactly the viewport dimensions.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added/updated unit tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes