Revert ":necktie: Store null responses separately"

This reverts commit cde47f2.

Author: shnizzedy

src/mindlogger_data_export/outputs.py

@@ -616,25 +616,10 @@ def _format(self, data: MindloggerData) -> list[NamedOutput]:
 
         # Format each activity for REDCap
         outputs = []
-        null_response_mask = pl.col("item_response") == "value: null"
         for wide_output in wide_outputs:
             activity_name = wide_output.name
-            # Split into responses and nulls
-            response_df = wide_output.output.filter(~null_response_mask)
-            null_df = wide_output.output.filter(null_response_mask)
-
-            # Add formatted responses to outputs
-            formatted_df = self._format_activity(response_df, activity_name)
-            if len(response_df) > 0:
-                outputs.append(
-                    NamedOutput(name=f"{activity_name}_redcap", output=formatted_df)
-                )
-
-            # Add null responses to separate table
-            if len(null_df) > 0:
-                outputs.append(
-                    NamedOutput(name=f"{activity_name}_null_responses", output=null_df)
-                )
+            formatted_df = self._format_activity(wide_output.output, activity_name)
+            outputs.append(NamedOutput(f"{activity_name}_redcap", formatted_df))
 
         return outputs