Fido's digs these days are as high-end as his masters' house. (Illustration by Monica Seaberry) Housing Boom Reaches Its Tail End: The DoghouseBY SAM ALIc.2006 Newhouse News Service \ [Newark, NJ] -- The housing market is going to the dogs. Literally. As real estate agents struggle with a slowdown in home sales, a new source of income has surfaced: selling doghouses to pampered pooches. Wipe that smirk off your face. The commissions are to die for. On a typical "human" house, commissions amount to about 5 percent of the sale price, with half the commission paid to the seller's...