Blueprint inputs from outputs

Blueprint installation inputs can now take their values from another installation's outputs with valueFromOutput, so endpoints, credentials, and other values one installation produces reach the installations that depend on them without anyone copying them by hand. Inputs can draw from any blueprint output or service installation Terraform output in the same environment, and secret outputs only ever feed secret inputs. When a producer's output changes, Ryvn updates its consumers, and while the producer isn't ready, consumers keep running as they are instead of deploying with missing values.