Bay seniors may not put much credibility in Zagat (after all the reviews are from people whose opinions have no more culinary validity than you or me). But occasionally Zagat comes up with an idea worth exploring. In this case a recent review of the City’s backyard garden restaurants. These patios are generally greener, quieter and more romantic. The Reverie Café in Cole Valley even sports a small watermall. Le Zinc has flocks of birds singing in the arbors. In Downtown Berkeley, La Note does it darndest to convince you are hanging out in the Cote d’Azur. Most come with the single most important piece of furniture for outdoor restaurants in town- space heaters.