Implemented locale initialization based on browser settings, added methods to determine locale from URL parameters and Accept-Language header, and updated app initialization to include locale setup.

src/app.h

@@ -99,6 +99,8 @@ private:
     Wt::WTimer *timeoutRemainingTimer_;
     bool isLoggedInAsAdmin {false};
     void setMetaTags();
+    void initLocale();
+    Wt::WLocale determineLocaleFromBrowser() const;
     void initApp();
     void reSetUser();
     Wt::WVBoxLayout *createVerticalLayout();