Guide Claude on using Vaadin Signals for reactive state management in Vaadin 25 Flow. This skill should be used when the user asks to "use signals", "manage state reactively", "share state between users", "use reactive state", "use ValueSignal", "use ListSignal", "use SharedValueSignal", "use SharedNumberSignal", "use SharedListSignal", "use SharedMapSignal", "use SharedNodeSignal", "use local signals", "use shared signals", "use computed signals", "bind signals to components", "bindText", "bindValue", "bindEnabled", "bindVisible", "bindChildren", or needs help with reactive UI updates, signal transactions, signal effects, signal bindings, or thread-safe state management in Vaadin Flow.