settings: add "note" type, shows as card

also comes with a "style" attribute, to apply a color to the aside it's
shown in. Used in User Page/Messages to mention the customize button,
and on User page w/ a critical color to mention the jellyfin login
requirement.

api.go

@@ -268,7 +268,7 @@ func (app *appContext) GetConfig(gc *gin.Context) {
 			val := app.config.Section(sectName).Key(settingName)
 			s := resp.Sections[sectName].Settings[settingName]
 			switch setting.Type {
-			case "text", "email", "select", "password":
+			case "text", "email", "select", "password", "note":
 				s.Value = val.MustString("")
 			case "number":
 				s.Value = val.MustInt(0)