I took a deep breath in, exhaled, and climbed higher, trusting my hands and feet on the pebble-sized knobs and deceptively present friction of Donner Summit’s granite slabs. I’ve spent my last two weekends climbing vertical faces and cliffs in the Tahoe region, casually flirting with gravity. So, it may come as a surprise to learn that I’m actually afraid of heights. “Why do it?” you ask. For some reason, taking the most inefficient, technical, …