The artificial intelligence trade that defined Wall Street for the better part of two years is showing cracks. After a relentless run-up in semiconductor and mega-cap technology stocks, a growing chorus of analysts and portfolio managers is warning that the easy money in AI has already been made — and that the next wave of outperformance will come from companies that actually use AI to transform their businesses, not the ones selling the picks and shovels. The shift in sentiment has been swift. Nvidia, which became the poster child of the AI boom, has seen its stock retreat from all-time highs as investors question whether the billions pouring into data centers will translate into proportional returns.…