feat: add realtime updates of interval and reservation

src/stores/realtime.ts

@@ -0,0 +1,21 @@
+import { defineStore } from 'pinia';
+import { client } from 'src/boot/appwrite';
+import { Interval } from './schedule.types';
+import { ref } from 'vue';
+import { RealtimeResponseEvent } from 'appwrite';
+
+export const useRealtimeStore = defineStore('realtime', () => {
+  const subscriptions = ref<Map<string, () => void>>(new Map());
+
+  const register = (
+    channel: string,
+    fn: (response: RealtimeResponseEvent<Interval>) => void
+  ) => {
+    if (subscriptions.value.has(channel)) return; // Already subscribed.  But maybe different callback fn?
+    subscriptions.value.set(channel, client.subscribe(channel, fn));
+  };
+
+  return {
+    register,
+  };
+});