refactor: remove close_session() function

- Remove close_session() wrapper function entirely
- Callers now directly manage browser/context lifecycle
- Reduces module to pure authentication functions only

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

utils/auth.py

@@ -124,21 +124,3 @@ def logout(main_frame: Frame, verbose: bool = True) -> None:
             print("Confirmation dialog not found, may have auto-logged out")
 
     time.sleep(2)  # Wait for logout to complete
-
-
-def close_session(browser: Browser, context: BrowserContext) -> None:
-    """
-    Close browser session
-
-    Args:
-        browser: Browser instance
-        context: Browser context
-    """
-    # Check if auto-close browser is enabled
-    auto_close = os.getenv("ERP_AUTO_CLOSE_BROWSER", "true").lower() in ("true", "1", "yes")
-
-    if auto_close:
-        context.close()
-        browser.close()
-    else:
-        print("Note: Browser not auto-closed (ERP_AUTO_CLOSE_BROWSER=false)")