use separated class files, use hpp header extension, update include model

src/app/browser/page.hpp

@@ -0,0 +1,41 @@
+#ifndef APP_BROWSER_PAGE_H
+#define APP_BROWSER_PAGE_H
+
+#include <gtkmm/notebook.h>
+
+namespace app::browser
+{
+    class Page : public Gtk::Notebook
+    {
+        public:
+
+            const bool SCROLLABLE = true;
+            const bool REORDERABLE = true;
+
+            class Navbar
+            {
+                public:
+
+                    Navbar();
+            };
+
+            class Body
+            {
+                public:
+
+                    Body();
+            };
+
+            Page();
+
+            void append(
+                char* request,
+                bool open = true,
+                bool focus = false
+            );
+
+            void update();
+    };
+}
+
+#endif // APP_BROWSER_PAGE_H