fix(playwright): update context.request.headers with actual playwright headers

[RohithPariki]

Problem

Request headers when using fingerprint generator or header generator are not saved in context.request.headers.

Root Cause

When browserforge injects headers, they bypass the Crawlee-level request headers list. Because the framework does not sync back the actual headers used by Playwright for the navigation, the context remains unaware of them.

Solution

Updated _playwright_crawler.py to retrieve the actual headers from Playwright's response.request and update the Crawlee context.request.headers after navigation.

Testing

Manual verification / static analysis. (Verified that actual Playwright headers are parsed into HttpHeaders).

Risk

Low risk. Modifies the state of context.request.headers after navigation, which ensures consistency with what was actually sent over the wire.

Issue

Closes #1055