fix: improve parameter validation to reject whitespace-only strings

- Add .strip() check to username, password, url validation
- Update error messages to clarify whitespace rejection
- Prevents bugs where whitespace-only strings pass validation

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

utils/auth.py

@@ -36,12 +36,12 @@ def login(
     import time
 
     # Validate required parameters
-    if not username:
-        raise ValueError("username is required")
-    if not password:
-        raise ValueError("password is required")
-    if not url:
-        raise ValueError("url is required")
+    if not username or not username.strip():
+        raise ValueError("username is required and cannot be empty or whitespace")
+    if not password or not password.strip():
+        raise ValueError("password is required and cannot be empty or whitespace")
+    if not url or not url.strip():
+        raise ValueError("url is required and cannot be empty or whitespace")
 
     # Launch browser
     browser = playwright.chromium.launch(headless=headless)