HF RL Explorer

Bug: UECM residuals are incorrect when created from ARDL

Bug: UECM residuals are incorrect when created from ARDL: a task in LegoFlow-SWE (Harbor dataset). When using UECM.from ardl() to create a UECM model from an ARDL model and then fitting it, the resid property of the resulting UECMResults object returns incorrect residuals.

The task

When using `UECM.from_ardl()` to create a UECM model from an ARDL model and then fitting it, the `resid` property of the resulting `UECMResults` object returns incorrect residuals.

Part of Lego-X/LegoFlow-SWE.