run parallel

Runs up to 5 selected functions in parallel to speed up execution, then continues the flow once all have finished. Each function's return values are exposed on its own result_N object pin. Sets success=false and a global error if any function fails.

Runs the 1-5 selected functions concurrently and blocks until ALL have finished, then continues the flow. Function N's return pins are emitted as an object on result_N (selection order); a function that returned nothing yields an empty object, never nil. success is true only when every function completed without error; on any failure success=false and error holds the FIRST failure. No function selected gives success=false with error NO_FUNCTIONS_SELECTED. Custom in-pins for function N are wired as block in-pins named f{N}_{pinId}.