The demand for help navigating the famously complex US health care system has propelled a startup called Solace Health to a $1 billion valuation — offering health advocacy for people trying to schedule appointments, interpret treatment plans and understand medical bills. Venture capital firm IVP led the financing, which brought in $130 million for the startup, Solace plans to announce Tuesday. Other investors include Menlo Ventures, SignalFire, Torch Capital, Inspired Capital and RiverPark Ventu...