Function get_global_task_manager 

pub fn get_global_task_manager() -> &'static TaskManager

Returns the process-wide shared TaskManager.

Initializes with ~/.gestura/tasks/ on first call; subsequent calls return the same instance. Callers must not create their own OnceLock<TaskManager> statics — doing so produces independent in-memory caches that cause stale reads when a different subsystem writes tasks to disk.