Service worker push handlers and client subscribe (Feature 19) (#156)

Co-authored-by: orchestrator-agent <20+orchestrator-agent@code.cubecraftcreations.com>

web/src/push/usePush.ts

@@ -0,0 +1,29 @@
+import { useMemo } from 'react'
+import { useApi } from '../api/ApiContext.tsx'
+import {
+  browserPushEnvironment,
+  subscribePush,
+  unsubscribePush,
+  type SubscribePushResult,
+  type UnsubscribePushResult,
+} from './subscribe.ts'
+
+export type Push = {
+  // subscribePush turns on Web Push on this device; call it only from a tap.
+  subscribePush(): Promise<SubscribePushResult>
+  // unsubscribePush turns off Web Push on this device.
+  unsubscribePush(): Promise<UnsubscribePushResult>
+}
+
+// usePush binds subscribePush and unsubscribePush to the app's API client
+// and this browser.
+export function usePush(): Push {
+  const api = useApi()
+  return useMemo(
+    () => ({
+      subscribePush: () => subscribePush(api, browserPushEnvironment()),
+      unsubscribePush: () => unsubscribePush(api, browserPushEnvironment()),
+    }),
+    [api],
+  )
+}