refactor: decompose backend services and routes for maintainability

backend/src/services/notifications/index.ts

@@ -0,0 +1,20 @@
+export {
+	buildPrescriptionReminderPushNotification,
+	buildStockReminderPushNotification,
+	type PrescriptionReminderItem,
+	type StockReminderItem,
+} from "./builders.js";
+export {
+	type EmailDeliveryRequest,
+	type EmailDeliveryResult,
+	getSmtpConfig,
+	sendEmailNotification,
+	sendPushNotification,
+} from "./delivery.js";
+export {
+	getReminderState,
+	loadReminderState,
+	saveReminderState,
+	updateReminderSentTime,
+	updateUserReminderSentTime,
+} from "./state.js";