Function phytrace_builder_build 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn phytrace_builder_build(
    builder: *mut PhyTraceBuilderHandle,
) -> *mut PhyTraceEventHandle

Build the event, consuming the builder.

Returns a heap-allocated event handle on success, or null on failure (e.g., validation error). On failure, the builder is still consumed/freed.

The returned event must be freed with phytrace_event_destroy() or consumed by phytrace_agent_send().