feat: 29 funciones TUI — constructores, runners y helpers del dominio tui

16 constructores puros (NewList, NewSpinner, NewProgress, DefaultStyles...),
4 runners impuros (RunModel, RunFullscreen, RunWithMouseSupport, Confirm),
5 print helpers impuros (PrintSuccess/Error/Warning/Info/Muted) y
4 utilidades puras (Quit, ClearScreen, HideCursor, ShowCursor).
Stubs que documentan devfactory/tui para el registry.

functions/tui/default_theme.go

@@ -0,0 +1,9 @@
+package tui
+
+// Implementation: github.com/lucasdataproyects/devfactory/tui
+
+// DefaultTheme crea el tema de colores por defecto.
+func DefaultTheme() Theme {
+	// stub — implementation in devfactory/tui
+	return Theme{}
+}