Implement the main menu for the ordoor binary

In this commit, we also remove code that doesn't properly belong in
view-menu

internal/ui/widget.go

@@ -25,6 +25,9 @@ type Widget struct {
 	OnMouseClick func()
 	OnMouseUp    func()
 
+	disabled      bool
+	disabledImage *ebiten.Image
+
 	// These are expected to have the same dimensions as the Bounds
 	hoverAnimation []*ebiten.Image
 	hoverState     bool
@@ -39,6 +42,13 @@ type Widget struct {
 	sprite *assetstore.Sprite
 }
 
+func (w *Widget) Disable() {
+	w.hovering(false)
+	w.mouseButton(false)
+
+	w.disabled = true
+}
+
 func (w *Widget) hovering(value bool) {
 	if w.OnHoverEnter != nil && !w.hoverState && value {
 		w.OnHoverEnter()
@@ -72,6 +82,10 @@ func (w *Widget) mouseButton(value bool) {
 }
 
 func (w *Widget) Image(aniStep int) (*ebiten.Image, error) {
+	if w.disabled {
+		return w.disabledImage, nil
+	}
+
 	if w.hoverState && w.mouseButtonState {
 		return w.mouseButtonDownImage, nil
 	}