Add main settings view and theme management functionality

Introduce a new `MainSettings` view for managing application settings, including language and theme selection. Implement theme management methods in the `setting` package to handle theme initialization, retrieval, and updates.

internal/application/setting/setting.go

@@ -22,6 +22,11 @@ type SettingContract interface {
 
 	GetFFplayPath() string
 	SetFFplayPath(path string)
+
+	ThemeInit()
+	GetThemes() map[string]ThemeInfoContract
+	GetTheme() ThemeInfoContract
+	SetTheme(themeInfo ThemeInfoContract)
 }
 
 type setting struct {