feat: Add page lifecycle hooks to BrowserPool

[Mantisus]

Description

Add four page lifecycle hooks to BrowserPool registered as decorators:

• pre_page_create_hook — called before page creation; browser_new_context_options is mutable, so the hook can affect how the page context is configured.
• post_page_create_hook — called after page creation.
• pre_page_close_hook — called before page close.
• post_page_close_hook — called after page close.

Issues

• Relates: Add post-navigation hooks and browser lifecycle hooks #1741

Testing

• Added new tests for BrowserPool.

[Copilot]

Pull request overview

This PR adds four page lifecycle hooks to BrowserPool — pre_page_create_hook, post_page_create_hook, pre_page_close_hook, and post_page_close_hook — registered as decorators, aligning Python's BrowserPool closer to the JS Crawlee browser pool API as described in issue #1741.

Changes:

• Four hook registration methods added to BrowserPool, each appending user-provided async callables to internal lists that are executed at the corresponding lifecycle point.
• Close hooks are implemented by monkey-patching page.close via _override_page_close after page creation.
• Comprehensive tests covering individual hook invocation, execution order, argument validation, and multiple hook registration.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/crawlee/browsers/_browser_pool.py	Adds hook storage lists, _execute_hooks helper, _override_page_close for close hooks, and four public hook registration methods with docstrings.
tests/unit/browsers/test_browser_pool.py	Adds six tests covering each hook type, execution order, and multiple hook registration.

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[vdusek]

Currently, I don't have enough time to review it properly manually, but here are a few comments from Claude. Consider them, please.

[vdusek]

And also could you please consider whether we should not document this feature somewhere?

[vdusek]

LGTM