A 32-year-old woman presents with acute onset of fever, chills, and a painful swollen lesion on her left forearm. On examination, there is a localized area of erythema, warmth, and fluctuance. Gram stain of the aspirated pus shows gram-positive cocci in clusters. Culture confirms Staphylococcus aureus. Which is the most common site of S. aureus skin and soft tissue infection in community settings?