feat(frontend) : add useNotifications composable with polling

frontend/composables/useNotifications.ts

@@ -0,0 +1,69 @@
+import type { Notification } from '~/services/dto/notification'
+import { useNotificationService } from '~/services/notifications'
+
+const POLL_INTERVAL = 2 * 60 * 1000 // 2 minutes
+
+export function useNotifications() {
+    const unreadCount = useState<number>('notification-unread-count', () => 0)
+    const notifications = useState<Notification[]>('notification-list', () => [])
+    const isLoading = useState<boolean>('notification-loading', () => false)
+
+    const service = useNotificationService()
+    let pollTimer: ReturnType<typeof setInterval> | null = null
+
+    async function fetchUnreadCount(): Promise<void> {
+        try {
+            unreadCount.value = await service.getUnreadCount()
+        } catch {
+            // Silently ignore polling errors
+        }
+    }
+
+    async function fetchNotifications(): Promise<void> {
+        isLoading.value = true
+        try {
+            notifications.value = await service.getAll()
+        } finally {
+            isLoading.value = false
+        }
+    }
+
+    async function markAsRead(id: number): Promise<void> {
+        await service.markAsRead(id)
+        const notif = notifications.value.find(n => n.id === id)
+        if (notif && !notif.isRead) {
+            notif.isRead = true
+            unreadCount.value = Math.max(0, unreadCount.value - 1)
+        }
+    }
+
+    async function markAllAsRead(): Promise<void> {
+        await service.markAllAsRead()
+        notifications.value.forEach(n => n.isRead = true)
+        unreadCount.value = 0
+    }
+
+    function startPolling(): void {
+        fetchUnreadCount()
+        pollTimer = setInterval(fetchUnreadCount, POLL_INTERVAL)
+    }
+
+    function stopPolling(): void {
+        if (pollTimer) {
+            clearInterval(pollTimer)
+            pollTimer = null
+        }
+    }
+
+    return {
+        unreadCount,
+        notifications,
+        isLoading,
+        fetchNotifications,
+        fetchUnreadCount,
+        markAsRead,
+        markAllAsRead,
+        startPolling,
+        stopPolling,
+    }
+}