Fix: Replace st.dataframe with simple markdown to avoid Arrow row index error

src/app/main_app.py

@@ -1,7 +1,6 @@
 ###############################################################
 # main_app.py — Agentic Language Partner UI (Streamlit)
 ###############################################################
-import pandas as pd
 import json
 import random
 import re
@@ -765,7 +764,6 @@ def ocr_tab(username: str):
 ###############################################################
 
 def flashcards_tab(username: str):
-    import pandas as pd
     import re
 
     # ---------------------------------------------------------
@@ -1057,23 +1055,16 @@ def flashcards_tab(username: str):
     # DECK AT A GLANCE (FULL WIDTH)
     # =======================================================
     st.markdown("---")
-    st.subheader("Deck at a glance")
-
-    if cards:
-        df_rows = []
-        for i, c in enumerate(cards, start=1):
-            df_rows.append({
-                "#": i,
-                "Front": c.get("front", ""),
-                "Back": c.get("back", ""),
-                "Score": c.get("score", 0),
-                "Reviews": c.get("reviews", 0),
-            })
-
-        df = pd.DataFrame(df_rows)
-        st.dataframe(df, height=min(500, len(cards) * 40 + 50), use_container_width=True, hide_index=True)
-    else:
-        st.info("No cards in this deck.")
+    with st.expander("Deck at a glance", expanded=False):
+        if cards:
+            for i, c in enumerate(cards, start=1):
+                front = c.get("front", "")
+                back = c.get("back", "")
+                score = c.get("score", 0)
+                reviews = c.get("reviews", 0)
+                st.markdown(f"**{i}.** {front} → {back} *(Score: {score}, Reviews: {reviews})*")
+        else:
+            st.info("No cards in this deck.")
 
 
 ###############################################################