This pull request includes several changes to the browser_use/agent module to enhance the handling of page summaries, improve the task memory, and update the testing and logging mechanisms. The most important changes include updates to the AgentOutput structure, improvements to the important_rules method, and modifications to the test cases.

Enhancements to AgentOutput structure:

• browser_use/agent/message_manager/service.py: Updated the current_state to include a page_summary and adjusted the action to include a click_element with an index.
• browser_use/agent/views.py: Added page_summary to the AgentBrain class.

Improvements to task memory and instructions:

• browser_use/agent/prompts.py: Added detailed instructions for page_summary in the important_rules method and included new guidelines for handling long tasks and extraction tasks. [1] [2]
• browser_use/agent/prompts.py: Modified the get_user_message method to include markers for task history memory and current state.

Updates to testing and logging:

• browser_use/agent/message_manager/tests.py: Updated test cases to include page_summary in the AgentOutput structure. [1] [2] [3]
• browser_use/agent/service.py: Added logging for page_summary in the _log_response method.

These changes aim to improve the agent's ability to handle and log detailed page summaries, maintain comprehensive task memory, and ensure robust testing and logging practices.