Fix TypeScript build error: use type-safe record update

frontend/app/dashboard/forecast/page.tsx

@@ -44,14 +44,18 @@ export default function ForecastPage() {
 
       // Sync running states from backend, but keep optimistic UI if it's still running
       if (s?.running_tasks) {
-        const backendRunning = Object.fromEntries(Object.entries(s.running_tasks).map(([k, v]) => [Number(k), v]))
+        const backendRunning: Record<number, boolean> = Object.fromEntries(
+          Object.entries(s.running_tasks).map(([k, v]) => [Number(k), !!v])
+        )
         setRunningIds(prev => {
-          const newState = { ...prev, ...backendRunning }
-          // Remove items that backend says are not running anymore
-          Object.keys(prev).forEach(id => {
-            if (!backendRunning[Number(id)]) delete newState[Number(id)]
+          const merged = { ...prev, ...backendRunning }
+          const cleaned: Record<number, boolean> = {}
+          // Hanya simpan yang memang masih running di backend
+          Object.entries(merged).forEach(([id, val]) => {
+            const nid = Number(id)
+            if (backendRunning[nid]) cleaned[nid] = true
           })
-          return newState
+          return cleaned
         })
       }
     } catch {}