Port durable automations and global pause as world extensions

extensions/pause/api.ts

@@ -0,0 +1,9 @@
+/** Pause: whether the user paused this Ultimate, for timers that start work outside the task scheduler. */
+const defineApi = <S>() => (name: string): {name: string; service?: S} => ({name})
+
+export type PauseService = {
+  /** Whether the host is paused; a timer that starts work (a fetch, a ping, a backup) skips its tick while it is. */
+  paused(): boolean
+}
+/** The pause; `want` it, pause is optional. */
+export const PauseApi = defineApi<PauseService>()('pause')