fix validation when string is empty for config

src/hf_eda_mcp/validation.py

@@ -117,14 +117,8 @@ def validate_config_name(config_name: Optional[str]) -> Optional[str]:
 
     config_name = config_name.strip()
 
-    if not config_name:
-        raise ValidationError(
-            "config_name cannot be empty or contain only whitespace",
-            suggestions=[
-                "Provide a valid configuration name or omit the parameter",
-                "Use None or don't specify config_name for default configuration",
-            ],
-        )
+    if len(config_name) == 0:
+        return None
 
     # Validate format: alphanumeric, hyphens, underscores, dots
     pattern = r"^[a-zA-Z0-9][\w\-\.]*$"