Implement a single-thread task scheduler API

Design and implement a simple task scheduler for a **single CPU, single thread** environment. You need to support scheduling callbacks (tasks) using the following APIs: - `scheduleOnce(task, runAtTime)` - runs `task` exactly once at the specified absolute time. - `scheduleWithDelay(task, delay)` - runs `task` exactly once after the specified delay from “now”. - `schedulePeriodic(task, initialDelay, period)` - runs `task` first after `initialDelay`, then repeatedly every `period`. ### Requirements - Only one task runs at a time (no parallelism). - If multiple tasks are due at the same time, execute them in a deterministic order (define one). - Define behavior if a periodic task’s next run time is missed because execution took too long. - Include how the scheduler waits/sleeps and wakes up to run the next task. ### Deliverable Describe the data structures and implement the scheduler logic.