refactor: migrate from MUI to Ant Design for layout and components

- Updated package.json to remove MUI dependencies and add Ant Design.
- Refactored App component to use Ant Design's Layout, Header, Footer, and Sidebar.
- Created new Footer, Header, and Sidebar components using Ant Design.
- Removed old Header component that used MUI.
- Updated Home component to use Ant Design's Typography and Button.
- Added global styles in index.less and theme styles in theme.less and layout.less.
- Removed MUI theme configuration and replaced it with Ant Design's theming.

frontend/src/theme/layout.less

@@ -0,0 +1,57 @@
+@import "theme.less";
+
+html, body, #root {
+  height: 100%;
+  min-width: 100%;
+  margin: 0;
+  padding: 0;
+}
+
+body {
+  background-color: @body-background;
+  color: @text-color;
+}
+
+.ant-layout {
+  background: @body-background;
+}
+
+.ant-layout-header {
+  background: @layout-header-background;
+  color: @text-color;
+  font-size: @font-size-header;
+  position: sticky;
+  top: 0px;
+  left: 0px;
+  overflow: auto;
+}
+
+.ant-layout-content {
+  background: @component-background;
+  min-height: calc(100vh - 64px - 70px); // header + footer height
+}
+
+.ant-layout-sider{
+  li span{  font-size: @font-size-slider;}
+  height: calc(100vh - 64px - 70px);
+  background: @component-background;
+  top: 64px;
+  overflow: auto;
+  position: sticky;
+}
+
+.ant-layout-footer {
+  background: @component-background;
+  color: @text-color-secondary;
+  text-align: center;
+  width: auto;
+}
+
+.ant-menu-dark {
+  background: @menu-dark-bg;
+  color: @text-color;
+}
+
+.ant-menu-dark .ant-menu-item-selected {
+  background-color: darken(@primary-color, 10%);
+}

frontend/src/theme/theme.less

@@ -0,0 +1,15 @@
+// Dark theme colors
+@primary-color: #1DA57A;
+@text-color: #ffffff;
+@text-color-secondary: #bfbfbf;
+@heading-color: #ffffff;
+@body-background: #141414;
+@component-background: #1f1f1f;
+@border-color-base: #434343;
+@border-radius-base: 8px;
+@font-size-base: 14px;
+@menu-dark-bg: #1f1f1f;
+@menu-dark-submenu-bg: #1a1a1a;
+@layout-header-background: #1f1f1f;
+@font-size-header: 24px;
+@font-size-slider: 18px;