Add a timescale to DGLC ice discharge

Based on thoughts from [this new paper](https://egusphere.copernicus.org/preprints/2025/egusphere-2025-1940/), the land ice team wants to try adding a 10-year (or otherwise adjustable) time lag to ice fluxes from DGLC to the runoff model. The thought is that this could reduce some of the immediate cold water fluxes into the lab sea area and reduce freezing.

The sea ice team has also suggested improved seasonality of freshwater fluxes from DGLC. In other words, instead of releasing ice fluxes equally each month, release most of the water in the summer. Part of this project will be an analysis of the feasibility of that request.