Bright light and serene river views enhance this loft-like, corner 6 1/2-room apartment.   Two East End Avenue, a 1908 warehouse converted to spacious luxury apartments, is located at 79th Street, a few steps from the East River Promenade and Carl Schurz Park.  Enter the apartment via a large foyer and 17gallery.  The quiet and comfortable living room has walls of windows looking East and South over the East River.  Entertain in the expansive dining area or enjoy the oversized, windowed eat-in kitchen, which offers ample space for the gourmet cook.  The magnificent 3 bedroom, 3 bath floor plan features high ceilings, a laundry room with large-capacity appliances and 3 huge walk-in closets.  In keeping with the grand layout, the 24 master bedroom boasts a dressing area, home office and southern exposure.  The pre-war building has a state-of-art- fitness center, full time doorman, bike room, trunk storage room and welcomes pets.  There is easy access to the crosstown and Wall Street express buses.