A regular square pyramid $ABCDE$ has base $ABCD$, which measures $4$ cm on a side, and its apex $E$ is $6$ cm directly above the center of the base. Point $P$ lies on $\overline{BE}$, halfway from $B$ to $E$. Point $Q$ lies on $\overline{DE}$, halfway from $D$ to $E$, and point $R$ lies on $\overline{CE}$, one third of the way from $C$ to $E$. What is the area, in square centimeters, of $△PQR$?