refresh on target update

src/main.ts

@@ -30,6 +30,7 @@ let selectedActivityTypes: Set<string> = new Set(['Running']);
 
 // Event listeners
 csvUpload?.addEventListener('change', handleFileUpload);
+targetAcwrInput?.addEventListener('input', handleTargetAcwrChange);
 helpButton?.addEventListener('click', () => helpPopover?.classList.remove('hidden'));
 helpClose?.addEventListener('click', () => helpPopover?.classList.add('hidden'));
 helpPopover?.addEventListener('click', (e) => {
@@ -38,6 +39,19 @@ helpPopover?.addEventListener('click', (e) => {
     }
 });
 
+function handleTargetAcwrChange(): void {
+    // Only refresh if we have activities loaded
+    if (allActivities.length === 0) return;
+
+    // Filter and render with new target ACWR
+    const filteredActivities = selectedActivityTypes.size > 0
+        ? allActivities.filter(activity => selectedActivityTypes.has(activity.activityType || ''))
+        : allActivities;
+
+    const targetAcwr = parseFloat(targetAcwrInput.value) || 1.3;
+    renderCharts(filteredActivities, targetAcwr);
+}
+
 function createActivityTypeFilters(activities: Activity[]): void {
     // Get unique activity types
     const activityTypes = new Set<string>();