feat: add user update functionality and theme management

frontend_admin/src/App.css

@@ -1 +1,17 @@
-@import "tailwindcss";
+@import "tailwindcss";
+
+/* Example: App.css */
+body.dark {
+  background: #222;
+  color: #fff;
+}
+
+body {
+  background: #fff;
+  color: #222;
+}
+
+html.dark body {
+  background: #222;
+  color: #fff;
+}