Task List Utilities

You are writing helper functions for a task list. Each helper should return a result without mutating the original `tasks` array.

1. `addTask(tasks, title)` should return a new array with a new incomplete task added.
2. `completeTask(tasks, taskId)` should return a new array where only the matching task is completed.
3. `removeTask(tasks, taskId)` should return a new array without the matching task.
4. `countIncompleteTasks(tasks)` should return the number of incomplete tasks.