TUI refactor

- Clean up, improved startup logic, initial conversation load
- Moved converation/message business logic (mostly) into `model/tui`

pkg/util/util.go

@@ -138,7 +138,7 @@ func SetStructDefaults(data interface{}) bool {
 
 		// Get the "default" struct tag
 		defaultTag, ok := v.Type().Field(i).Tag.Lookup("default")
-		if (!ok) {
+		if !ok {
 			continue
 		}