My dream is a cliché, and I’m at peace with it:  Boy gets border collie, boy introduces border collie to sheep, border collie likes sheep, boy chucks it all to become a shepherd.  The story reached its logical conclusion, ad absurdum, when I moved to a 56-acre hill farm in southwestern New Hampshire this October.   In my defense, my longing to live somewhere rural began many years earlier, intensifying when I adopted Musti. I found myself spending every free moment exploring the local parks and forests with him; Boston’s urban playground, whose appeal was already fading, became a barrier rather than a perk.  Shortly after Luc joined us, the vague sense of needing to get out of the city sharpened considerably  — must…