Refactor browser agent and update dependencies

- Updated import statements to use 'patchright' instead of 'playwright'.
- Cleaned up the BrowserUseAgent class for better readability.
- Modified README instructions for browser installation.
- Added new entries to .gitignore for PDF files and workflow.

README.md

@@ -68,12 +68,7 @@ uv pip install -r requirements.txt
 Install Browsers in Playwright:
 You can install specific browsers by running:
 ```bash
-playwright install --with-deps chromium
-```
-
-To install all browsers:
-```bash
-playwright install
+patchright install chromium
 ```
 
 #### Step 4: Configure Environment