Fix playwright testing issues

[RatulMaharaj]

This pull request includes several changes to improve the testing framework and streamline the code in the src/agent directory. The most important changes include updating the testing framework from Cypress to Playwright, modifying subprocess commands for consistency, and ensuring the correct handling of test directories and unique image files.

Framework Update:

• config.toml: Changed the testing framework from Cypress to Playwright.

Subprocess Command Modifications:

• src/agent/scaffold.py: Updated subprocess commands to use a consistent format without list brackets for node, npm, playwright, and cypress commands. [1] [2] [3] [4] [5] [6] [7] [8] [9]

Directory Handling:

• src/agent/tools.py: Ensured the tests directory exists when writing code and running tests for Playwright. [1] [2]
• src/agent/utils.py: Added code to ensure the test_dir exists before running Playwright tests.

Image Handling:

• src/agent/video.py: Renamed find_unique_images to keep_unique_images and extended it to handle multiple image formats (png, jpeg, jpg, webp). [1] [2]
• src/agent/utils.py: Integrated keep_unique_images into the screenshot checking process to handle additional image formats. [1] [2]

Minor Changes:

• src/agent/cli/init.py: Removed the redundant HEADLESS environment variable initialization.
• src/agent/utils.py: Imported keep_unique_images from agent.video.