Defense startup Shield AI has finalized a deal to raise $240 million from investors at a valuation of $5.3 billion — a funding round that adds billions to the company’s valuation, and underscores Silicon Valley investors’ interest in drones, autonomy and national security technology. The San Diego-based startup plans to use the cash infusion to expand its software offerings. Variations of Shield AI’s Hivemind software can pilot autonomous vehicles as well as help companies build their own autono...