HE WAS ESCORTING A FALLEN SOLDIER — THE AIRLINE TRIED TO STOP HIM. BIG MISTAKE. The morning rush at Gate 23 felt like every other: boarding calls blaring, espresso machines hissing, business suits tapping impatiently at phones. Outside the glass, a flag-draped casket waited in the wind. Inside, one man stood motionless at the counter — Colonel David Carter, travel orders folded neatly in his hand. He'd been assigned to bring home a 23-year-old private killed overseas. A simple duty, sacred and q