A California state court case over whether Instagram and YouTube harmed a woman’s mental health through addictive app design kicks off on Monday with opening statements, in a test of whether Big Tech platforms can be held liable for harming kids. The 20-year-old woman identified as K.G.M. filed the lawsuit against Facebook and Instagram parent company Meta Platforms and Alphabet’s Google, which owns YouTube. She says the attention-grabbing design of the platforms got her addicted to them at a...