feat: header fraction KPIs replacing KPI row (Task 10.3)

Remove KPI card row, add 3 inline fraction KPIs to header bar:
filtered/total patients, drugs, cost. Breadcrumb removed.
KPI callback refactored for 6 output IDs (3 filtered + 3 total).
total_cost added to load_initial_data() reference data.

dash_app/callbacks/kpi.py

@@ -1,4 +1,4 @@
-"""Callback for updating KPI card values from chart-data store."""
+"""Callback for updating fraction KPI values in the header bar."""
 from dash import Input, Output, no_update
 
 
@@ -12,30 +12,49 @@ def _format_cost(cost):
 
 
 def register_kpi_callbacks(app):
-    """Register KPI update callback."""
+    """Register header KPI update callbacks."""
 
     @app.callback(
-        Output("kpi-patients", "children"),
-        Output("kpi-drugs", "children"),
-        Output("kpi-cost", "children"),
-        Output("kpi-match", "children"),
+        # Filtered values (numerators)
+        Output("kpi-filtered-patients", "children"),
+        Output("kpi-filtered-drugs", "children"),
+        Output("kpi-filtered-cost", "children"),
+        # Total values (denominators)
+        Output("kpi-total-patients", "children"),
+        Output("kpi-total-drugs", "children"),
+        Output("kpi-total-cost", "children"),
         Input("chart-data", "data"),
-        Input("app-state", "data"),
+        Input("reference-data", "data"),
     )
-    def update_kpis(chart_data, app_state):
-        """Update KPI card values when chart-data changes."""
-        if not chart_data:
-            return no_update, no_update, no_update, no_update
+    def update_header_kpis(chart_data, ref_data):
+        """Update header fraction KPIs from chart-data (filtered) and reference-data (totals)."""
+        # Filtered values from chart-data
+        if chart_data:
+            patients = chart_data.get("unique_patients", 0)
+            drugs = chart_data.get("total_drugs", 0)
+            cost = chart_data.get("total_cost", 0.0)
+            filtered_patients = f"{patients:,}" if patients else "\u2014"
+            filtered_drugs = str(drugs) if drugs else "\u2014"
+            filtered_cost = _format_cost(cost) if cost else "\u2014"
+        else:
+            filtered_patients = "\u2014"
+            filtered_drugs = "\u2014"
+            filtered_cost = "\u2014"
 
-        patients = chart_data.get("unique_patients", 0)
-        drugs = chart_data.get("total_drugs", 0)
-        cost = chart_data.get("total_cost", 0.0)
+        # Total values from reference-data
+        if ref_data:
+            total_patients_val = ref_data.get("total_patients", 0)
+            total_drugs_val = len(ref_data.get("available_drugs", []))
+            total_cost_val = ref_data.get("total_cost", 0.0)
+            total_patients = f"{total_patients_val:,}" if total_patients_val else "\u2014"
+            total_drugs = str(total_drugs_val) if total_drugs_val else "\u2014"
+            total_cost = _format_cost(total_cost_val) if total_cost_val else "\u2014"
+        else:
+            total_patients = "\u2014"
+            total_drugs = "\u2014"
+            total_cost = "\u2014"
 
-        patients_str = f"{patients:,}" if patients else "\u2014"
-        drugs_str = str(drugs) if drugs else "\u2014"
-        cost_str = _format_cost(cost) if cost else "\u2014"
-
-        chart_type = (app_state or {}).get("chart_type", "directory")
-        match_str = "~93%" if chart_type == "indication" else "\u2014"
-
-        return patients_str, drugs_str, cost_str, match_str
+        return (
+            filtered_patients, filtered_drugs, filtered_cost,
+            total_patients, total_drugs, total_cost,
+        )