Simplify overview_by_order_status function

- Refactor overview_by_order_status to use COLUMN_TO_AGGFUNC constant
- Rename value_col parameter to column for consistency
- Remove redundant title setting in update_layout
- Update target in app.py to use "column" parameter name

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app.py

@@ -115,7 +115,7 @@ overview_page = vm.Page(
             targets=[
                 "region_bar_chart.value_col",
                 "category_bar_chart.value_col",
-                "order_status_pie_chart.value_col",
+                "order_status_pie_chart.column",
                 "month_line_chart.column",
                 "segment_bar_chart.value_col",
             ],

charts.py

@@ -318,38 +318,20 @@ def overview_by_month(data_frame, column="Sales"):
 
 
 @capture("graph")
-def overview_by_order_status(data_frame, value_col="Sales"):
-    """Pie chart showing distribution by Order Status."""
-    if value_col == "Order ID":
-        status_metric = (
-            data_frame.groupby("Order Status", as_index=False)["Order ID"]
-            .nunique()
-            .rename(columns={"Order ID": "Orders"})
-        )
-        agg_col = "Orders"
-    elif value_col == "Customer ID":
-        status_metric = (
-            data_frame.groupby("Order Status", as_index=False)["Customer ID"]
-            .nunique()
-            .rename(columns={"Customer ID": "Customers"})
-        )
-        agg_col = "Customers"
-    else:
-        status_metric = data_frame.groupby("Order Status", as_index=False)[value_col].sum()
-        agg_col = value_col
+def overview_by_order_status(data_frame, column="Sales"):
+    grouped_df = data_frame.groupby("Order Status", as_index=False).agg({column: COLUMN_TO_AGGFUNC[column]})
 
     fig = px.pie(
-        status_metric,
+        grouped_df,
         names="Order Status",
-        values=agg_col,
+        values=column,
         color="Order Status",
-        title=f"{agg_col} by Order Status",
+        title=f"{column} | By Order Status",
         color_discrete_map={"In Transit": PRIMARY_COLOR, "Processing": ORANGE_COLOR, "Delivered": GREEN_COLOR},
         hole=0.6,
     )
 
     fig.update_layout(
-        title=f"{agg_col} | By Order Status",
         legend={"yanchor": "bottom", "y": -0.2, "xanchor": "right", "orientation": "v"},
     )