Function set_trace_enabled 

pub fn set_trace_enabled(enabled: bool) -> bool

Enables or disables profiler trace collection at runtime.

When transitioning from enabled to disabled, add_task_timing becomes cheaper since only cheap statistics are gathered. The existing per-thread task buffers and the frame-event buffer are cleared so stale data isn’t reported after a later re-enable. Active trace scopes keep collection enabled until the last scope ends. Calls with the current setting are a no-op.