feat(phase-18): add in-app notification system (T-128, T-129)

frontend/src/api/notifications.ts

@@ -0,0 +1,51 @@
+import client from "./client";
+
+// ── Types ───────────────────────────────────────────────────────────
+
+export interface NotificationItem {
+  id: string;
+  user_id: string;
+  type: string;
+  title: string;
+  message: string | null;
+  entity_type: string | null;
+  entity_id: string | null;
+  read: boolean;
+  created_at: string | null;
+}
+
+export interface UnreadCount {
+  unread_count: number;
+}
+
+// ── API ─────────────────────────────────────────────────────────────
+
+/** Fetch notifications for the current user (paginated). */
+export async function getNotifications(
+  offset = 0,
+  limit = 20,
+): Promise<NotificationItem[]> {
+  const { data } = await client.get<NotificationItem[]>(
+    `/notifications?offset=${offset}&limit=${limit}`,
+  );
+  return data;
+}
+
+/** Get the unread notification count. */
+export async function getUnreadCount(): Promise<UnreadCount> {
+  const { data } = await client.get<UnreadCount>("/notifications/unread-count");
+  return data;
+}
+
+/** Mark a single notification as read. */
+export async function markAsRead(id: string): Promise<NotificationItem> {
+  const { data } = await client.patch<NotificationItem>(
+    `/notifications/${id}/read`,
+  );
+  return data;
+}
+
+/** Mark all notifications as read. */
+export async function markAllAsRead(): Promise<void> {
+  await client.post("/notifications/read-all");
+}