Refactor imports for PEP 8 compliance and clarity

- Organized imports in browser_manager.py by category (stdlib, 3rd-party, local)
- Organized imports in browser_profiler.py by category
- Cleaned up test file imports for consistency
- All imports alphabetized within their categories

Co-authored-by: Ahmed-Tawfik94 <106467151+Ahmed-Tawfik94@users.noreply.github.com>

tests/browser/test_cdp_concurrency.py

@@ -8,15 +8,19 @@ in managed browsers (CDP mode) work correctly, particularly:
 3. Multiple concurrent arun_many calls work correctly
 """
 
+# Standard library imports
 import asyncio
-import pytest
-import sys
 import os
+import sys
+
+# Third-party imports
+import pytest
 
 # Add the project root to Python path
 sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '../..')))
 
-from crawl4ai import AsyncWebCrawler, BrowserConfig, CrawlerRunConfig, CacheMode
+# Local imports
+from crawl4ai import AsyncWebCrawler, BrowserConfig, CacheMode, CrawlerRunConfig
 
 
 @pytest.mark.asyncio