First thought: Getting to the optimal heating & cooling solutions requires a careful calculation of the actual loads, room by room, zone by zone. If this were a residence ACCA Manual-J would be the rigth methodology. Some of it is residential, some of it isn't. There are code requirements for ventilation rates for commercial & industrial buildings based on occupancy and activity that will affect the load numbers. These numbers should be calculated by a competent third party such as a certified professional engineer (who makes all their money on the accuracy of their numbers) , not an HVAC contractor (who makes most of their money on selling & installing equipment.)
Second thought: The outdoor summertime dew points in Chelan are low enough that latent cooling loads are negative, and that chilled water in a radiant slab could provide the bulk of the cooling (unless this place has an un-insulated roof and a lot of west facing windows, which doesn't appear to be the case) forcing the necessary water temps to be too low. A
reversible chiller adequate for the cooling load would very likely be able to handle the heating load at slab-radiant heating water temperatures. But you need to know the loads to be able to calculate the water temperature requirements for both heating and cooling.
Chelan's
1% and 99% outside design temperatures are about 91F and +8F, which isn't a problem for reversible chillers, and it would use only about 1/3 the amount of power of an electric boiler in heating mode if sized correctly. Even though electricity is cheap, it's not free, and the combined mechanical system will probably come in cheaper than separate heating & chilled water cooling systems, given that you're already springing for the chiller, and you can probably reduce the number of (or even eliminate) the chilled water fan coils or whatever you were planning on. Radiant slab cooling doesn't work everywhere, but you're in a sufficiently dry-air location that it most likely can, with
mid-summer outdoor dew points below 55F more than 90% of the time, usually well under 50F. You can probably cool the place with just the slab to under 75F with 60-65F water (just a WAG, without the load numbers), with essentially no risk of condensation on the plumbing or slab, using cooler water on a fan-coil or two if more cooling is needed.
The same wall coils (if any) used for cooling could also be used for more heating capacity to help keep the maximum water temps down, efficiency & capacity up, or worst-case, add an electric boiler to the loop for those few hours when the capacity of the chiller is falling short, or to the zones that still need to be fully heated when temps are below +10F outside.
Third thought: Hire a competent mechanical engineer. This type of project has way too many parts to it to be amenable to "design by web forum". But the upcharge for a reversible chiller over a cooling only chiller is "in the noise" of a project like this, and you might as well make use of the slab.