Pre-populate username (#185)

* Pre-populate username

If a username is set, charm now pre-populates the input field with it
in the "set username" section. Resolves #16

* refactor: simplify username handling

---------

Co-authored-by: bashbunni <bunni@bashbunni.dev>

ui/username/username.go

@@ -94,11 +94,15 @@ func NewModel(cc *client.Client) Model {
 
 	im := input.New()
 	im.CursorStyle = st.Cursor
-	im.Placeholder = "divagurl2000"
 	im.Prompt = st.FocusedPrompt.String()
 	im.CharLimit = 50
 	im.Focus()
 
+	im.Placeholder = "divagurl2000"
+	if u, err := cc.Bio(); err == nil && u.Name != "" {
+		im.Placeholder = u.Name
+	}
+
 	return Model{
 		Done:    false,
 		Quit:    false,