I doubt if the engine seized if you can rotate it with your hands.
More than likely, it shut down as most modern engines have sensors that shut it down before real engine damage is done.
fill with oil and crank to start, if it runs listen for any knocking that should quiet some as it runs and watch the temperature gauge.
if it does, take to your mechanic - an tuneup and new oil should work. if it ran till it shut down w/o, there has been some stress on plugs, filter and coolant. may want to change that thermostat on the way. among other recomendations from your mechanic.
experience from a 92 marquis, no serious damage.
since the car was paid for and mint, I went for the timing chain replacement (uses 2), oil pump, water seals, valve job and regasket. could not do nothing about the start up knocking that went away after a minute. did thermostat and clutch along the way... short about 1500 now.. parts and labor.