OPEN HOUSES CANCELED, OFFER ACCEPTED.    Architect-designed Contemporary/Colonial in Kendall Gardens.   Abutting Beaver Brook Reservation, this impeccably-maintained home offers space, light and privacy within a park-like setting.  The open first floor plan features a chef's kitchen with gas cooking, abundant cabinets, double-ovens, a comfy den with gas fireplace and radiant floor heating.  Oversized floor-to-ceiling windows and skylights bathe the house in all-day sun and the double-deck off the kitchen is ideal summer dining.  The oasis back yard is truly serene and offers dramatic sunsets and great bird watching.  Other features include a separate home office, formal fireplaced living room, a 2nd floor library, modern tiled bathrooms, 6-zone gas heating, completely finished walk-out basement with fireplaced play room, a spacious laundry room and large exercise room.  The 3rd floor master suite with vaulted ceilings and skylights is a peaceful retreat.