Änderung: parquet_store.py

app/tools/excel_export.py

@@ -0,0 +1,16 @@
+import pandas as pd
+import io
+
+def df_to_excel_bytes(df):
+
+    """
+    Convert a DataFrame to an in-memory XLSX file.
+
+    Returns a BytesIO object suitable for st.download_button(data=...).
+    """
+
+    buffer = io.BytesIO()
+    with pd.ExcelWriter(buffer, engine="openpyxl") as writer:
+        df.to_excel(writer, index=False, sheet_name="Daten")
+    buffer.seek(0)
+    return buffer