Function phytrace_last_error 

#[unsafe(no_mangle)]
pub extern "C" fn phytrace_last_error() -> *const c_char

Retrieve the last error message from the FFI layer.

Returns a pointer to a null-terminated UTF-8 string describing the last error. Returns null if no error has occurred. The returned string is valid until the next FFI call on the same thread. Caller must NOT free this pointer.