Fix pandas Styler cell limit error for large datasets

Added conditional styling logic to avoid StreamlitAPIException when
dataframes exceed 262,144 cells (pandas styler limit). Now only applies
color styling to Grade column when dataset is small enough (< 100K cells).
For large datasets, displays plain dataframe with info message.

Fixes error when loading All organizations (38,995+ records).

Author: jonero1

data_explorer.py

@@ -1284,8 +1284,15 @@ def color_grade(val):
             color = get_quality_color(val)
             return f'background-color: {color}; color: #000000; font-weight: bold;'
 
-        styled_df = site_df.style.applymap(color_grade, subset=['Grade'])
-        st.dataframe(styled_df, use_container_width=True, height=400)
+        # Only apply styling if dataframe is small enough (avoid pandas styler limits)
+        total_cells = site_df.shape[0] * site_df.shape[1]
+        if total_cells <= 100000:  # Safe limit for pandas styler
+            styled_df = site_df.style.applymap(color_grade, subset=['Grade'])
+            st.dataframe(styled_df, use_container_width=True, height=400)
+        else:
+            # For large datasets, display without styling
+            st.dataframe(site_df, use_container_width=True, height=400)
+            st.info(f"ℹ️ Grade colors disabled for large dataset ({len(site_df):,} rows)")
 
         # Top 5 sites needing improvement
         st.markdown("#### 🔧 Top 5 Sites Needing Improvement")
@@ -1327,8 +1334,16 @@ def color_grade(val):
             })
 
         org_df = pd.DataFrame(org_scores)
-        styled_org_df = org_df.style.applymap(color_grade, subset=['Grade'])
-        st.dataframe(styled_org_df, use_container_width=True, height=400)
+        
+        # Only apply styling if dataframe is small enough (avoid pandas styler limits)
+        total_cells = org_df.shape[0] * org_df.shape[1]
+        if total_cells <= 100000:  # Safe limit for pandas styler
+            styled_org_df = org_df.style.applymap(color_grade, subset=['Grade'])
+            st.dataframe(styled_org_df, use_container_width=True, height=400)
+        else:
+            # For large datasets, display without styling
+            st.dataframe(org_df, use_container_width=True, height=400)
+            st.info(f"ℹ️ Grade colors disabled for large dataset ({len(org_df):,} rows)")
 
         # Top 5 organizations needing improvement
         st.markdown("#### 🔧 Top 5 Organizations Needing Improvement")