feat: add frontend entry point, theme, and router

frontend/src/theme.ts

@@ -0,0 +1,17 @@
+import { createTheme } from '@mui/material/styles'
+
+export const theme = createTheme({
+  palette: {
+    mode: 'light',
+    primary: { main: '#3b82f6' },
+    background: { default: '#f5f7fa', paper: '#ffffff' },
+  },
+  components: {
+    MuiAppBar: { styleOverrides: { root: { backgroundColor: '#1a1f2e' } } },
+    MuiDrawer: {
+      styleOverrides: {
+        paper: { backgroundColor: '#1a1f2e', color: '#e2e8f0', borderRight: 'none' },
+      },
+    },
+  },
+})